Sam,
Depends on where you plan to spend most of your time. In the Anchorage area, get in touch (in advance) with Heidi Reuss, or her son Richard, at Arctic Flyers. They have a couple of Taylorcrafts on floats, and will probably be the least expensive float deal you'll find up there. They also do a really good job of instructing. All very high time float pilots.
Anchorage is a long way from Denali, but it would be possible to do that with a t-craft, I suppose, if you wanted to fly up there. The T-craft on floats is somewhat limited on altitude capability, though. And McKinley is sorta tall.
Consider this: Work on your Dad to take the "flight of a lifetime". Get him to pay

. Get in touch with K-2 Aviation, based in Talkeetna. They are, in my opinion, one of the two best operators on the mountain. The other is Hudson Air. They both operate out of Talkeetna. If you're there early summer, they'll still be landing on glaciers on the mountain. I spent 30 years up there, and I will tell you without hesitation that a sightseeing flight around McKinley is worth every penny it costs, no matter how much that is. It is a spectacular place, and those folks are good at showing it off. The deepest canyon in north America is the Great Gorge of the Ruth Glacier. Anyway you can work it, get a ride around the mountain, but do it with one of these folks. It can be a tough place to fly at times, so best to do it with the pros. Any floatplane short of a turbine is NOT going to get you where you want to be around teh mountain, though.
Other options for float training: Alex at Dragonfly Air in Homer--He has a PA-11 on floats.
There are a couple other float operators around Lake Hood in ANC. Lake Hood is a spectacle itself. Several hundred floatplanes, and there are times when it seems they all leave at once. Great fun to just walk around and watch aviation happen. And, cheap.
Talkeetna is a funky little place, especially in the climbing season. Busy, though.
Fairbanks is further from everything, so costs more to go from there to other places. Great place, and my home for 20 years, though.
Give me more specifics on where you plan to be and maybe that will trigger a few more bits of gray matter.
MTV