While perusing the following, please remember that while this writer's idea of a "five star" rating requires only the availability of scotch (or a reasonable facsimile), the ability to find a decent steak now and again (or the reasonable facsimile) and no insurmountable bug problems that Amway's Hour Guard 12 can't handle (and I haven't found anything it can't), your desired itinerary may demand a tad more luxury and civility.
But these destinations were chosen solely for their ability to provide endorphin-stimulated relaxation...so have at them.
Best Bang for Your Adventure Travel Dollar
Hands down winner is Vietnam. I spent 27 months there during the Second Southeast Asian War Games and another six weeks in the early 90s, and I prefer the latter to the former (needless to say). But don't miss the war attractions like the tunnels at Cua Loa or the city of Hue. Bus travel can be dangerous, but damn exciting, especially when crossing from the former "north" to the former "south," but it's a great way to see the country.
Local cuisine may take some getting used to but — aside from the airfare — Vietnam is still the best place to stretch your travel dollars (or dongs, as the local currency is called). There is some good surf between Dong Ha and Vung Tau (November through March is the best), and ample opportunity for sea kayaking, bouldering (see "climbing big rocks with no ropes"), diving, and all round "oh $#*!, this should be interesting" adventures. Add a plus if you're a Vietnam vet.
Best All-Weather Adventure Spot
By "all-weather" I mean you'll get all weather no matter when you go to the Falkland Islands. With 2,200 people spread over 645 square miles (2,000 of them in the capital of Stanley) and over 700 islands, you'll see, touch, and experience shipwrecks, penguins, seals, orcas, history, and weather that changes roughly every 45 minutes from shortpants-warm to anorak-snow and cold. Difficult — and expensive — to get to, but well worth it. Go via Santiago, Chile. This is a wreck diver's cold water paradise, but a yomp (as the Brits call it) anywhere is sure to turn up something unusual. Don't miss the rivers of stone or the par-three golf course at Goose Green. It features the roughest rough there is — landmines. A taste for things ovine helps, but decent burgers can be found at the Upland Goose, as can all manner of people who've bumped into the Malvinas (the Argentinian name for the Falkland's) either intentionally or accidentally.
Best Tropical Adventure Destination
Belize is hands down the best destination there is for the unusual. Want to roam real jungles with spider monkeys throwing things at you all while dodging British Army Gurkhas on training exercises? How about checking out Mayan ruins both discovered and undiscovered? Four-by-fouring on ice-slick clay jungle roads? There are rainforest canopy trails, 747-hangar-size cave systems, rope bridges, hand ferries, exotic private and semi-private cayes. English is the primary language (it was once British Honduras) and the southern coast is still serious wild. You must check out Club Vietnam on the Western Highway to San Ignacio. Great diving and fishing offshore, great exploring. Nothing to recommend in the cities, but the "burbs" are teriffic.
Best Not-So-Tropical Adventure Destination
Eh? Nova Scotia. Ride the tidal bore on the Schubenacadie River where the eagles are as rare as Long Island gulls, tour Cape Breton thus saving yourself a trip to France, watch the tide go out in the Bay of Fundy, learn to say "loony" unaffectedly as you party in local pubs...all with our friendly relatives to the north. Cycling on an excellent road system works, but so does sea kayaking the coast. This is also a major motorcycle touring destination. Biggest hidden secret? The surf is verrry good (bring your winter 4/5 in summer or any other time). You can also try your hand at some great fishing — both fresh and salt - and the bear hunting by bow or firearm is both pretty darn good and not easy. Optional side trips: Take a ferry to Labrador and Prince Edward Island, two places you have to go to because they exist and you're in the neighborhood.
Best Under-Appreciated Caribbean Island for Adventure
No guffaws, but my favorite Carib island (and I've been on most) for the action aficionado is Puerto Rico. Get out of San Juan intact and you'll find a country with more adventure that you can shake a stick at. Whether it's big wave surfing; rappelling to a river, then floating it to its cave terminus; finger-ripping bouldering; butt-kicking downhill mountain biking; or hairball hangliding, Puerto Rico offers it. And none of it is anywhere near any tourist centers. The folks are friendly as hell and it's one of two places (the other being Merida in the Yucatan) I've been where they don't look down on your rudimentary Spanish as long as you're trying. Rent a car, get out of San Juan and start driving (if a road looks direct or your GPS says it is ... it isn't). Nonetheless, from an adventurer's POV, PR is one very overlooked Caribbean island. Hint: check out the east coast where the locals have had a chance to develop the Vieques area, the former Roosevelt Roads military base.
Best US Mountain Adventure Town
My shoulders are now long gone, but every winter for about 20 years I Mecca'd out to Ouray for a week. To do what? To go ice climbing, because this is ice climbing central. Located on the other side of Telluride, in the summer you have everything the Rocky Mountains have to offer, but winter...ahh, winter.
The folks in Ouray have a slot canyon just walking distance from their main street. Somebody got the great idea that cold-plus-water-plus-vertical-canyon would equal ice and Ouray became an ice jock's must-do. As long as it's cold, there are short but vertical-and-beyond "problems" to solve with axe and crampons. If you're in reasonable shape and want to feel like Sir Edmund on Everest, this is the place to learn. Town offers a huge natural-hotspring-heated swimming pool and some nearly two dozen bars and restaurants (they filmed True Grit in the area and the Duke and cast hung out at The Outlaw Bar. If you're a Duke guy, you gotta go there). If you don't want to climb, there's cross-country and back-country skiing, snowmobiling, and some seriously beautiful winter scenery.
Best Place in Florida You've Never Been
While torn between two places, one in the north (around the Gainesville area...not for its college charm, but for its underwater caving), Everglades City is the most likely place you haven't been. And there's even a Long Island connection with this town at the literal end of the road. If you've read any or all of East Hampton author Peter Matthiesen's Watson Trilogy, Everglades City is where the climax occurs (at Ted Smallwood's store, now a museum/store), and it's a fixture in all three books (Killing Mr. Watson, Lost Man's River and Bone by Bone), and now four with Matthiessen's reworking of the first three into Shadow Country.
Get off Alligator Alley (Interstate 75) at Route 29 south to Everglades City and Chokoloskee Island — the gateway to Florida's 10,000 Islands area for some world class backcountry flats fishing (tarpon included), great paddling adventures (especially in the winter), flatland bicycle touring, terrific birding and wildlife viewing, and a great place to use as a base area for touring that ocean of grass known as the Everglades.