Thanks for posting, everybody. R2R has been on my "maybe I'll do that someday" list for years. Maybe I’ll get serious about it now. The heat will definitely affect me more than the altitude on Whitney.
Bob, I think it would be a cake walk for you! The bigger part of the issue, though, is the logistics of getting back to your car. You can pay a shuttle service, but there is the problem of where to spend the night (either before starting, or after the hike.)
North rim options are particularly scarce, South Rim not so bad, if you maybe extend your search to the town of Tusayan, ~five miles from the rim. ...This might work, but I haven't checked things out: Drive to north rim, spend night maybe in the car (could even be outside the GC boundary, but the drive is farther "in" to the trail head.) Hike across, have a room lined up, as close as possible (likely in Tusayan). Next day take a shuttle back to N. rim. I highly recommend doing it in May -- as soon as the N. rim is open to the public. Temps at the bottom are already ~90 at the river in May.
If you line up ideal accommodations, you need to start up to a year in advance.
By the way, for Bob and Steve Ch: I ended up carrying a quart of water through the entire hike without using it -- I was worried about emergencies (and the heat). I saw where I needed to ask (and I did the day before the hike) about the availability of water at the usual water stops, and was told they were all operational. By drinking a pint or more at each stop, I really didn't need to carry the extra several pounds of water. Of course, the temperature wasn't so bad on my hike.
Another BTW: Say, with Steve and his buddy going, and Bob interested, you guys could set up a car and key swap situation. That really does make it easier to plan the trip. I guess the biggest issue is that one party might bail on the trip.
If you have long-term plans, and can set it up, this is another possibility: Set up lodging overnight at either end, hike across one day, spend the night, then hike back the next. I talked with a woman at Phantom Ranch who was doing that.
