It's great to hear that a dry suit works in air temps into the 70's.
Something else to think about on this subject: We had a great outing this past Sunday wearing our drysuits, fleece drysuit liner and sweats. It was 100% sunny and when the wind got up to 15-20, we started getting a tad chilly. When we got home the air temperature was 72 degrees.
Why did we start getting chilly? The water temp has fallen to 50 degrees here. Even though the over land air temperature was in the 70's, it was well below that 1 foot above the water where we were.
I'm not familiar with dive booties. Do they go up high on your leg?
I don't have dive booties, but since you mention possibly getting a drysuit...We bought these Kokatat Scouts:
Got them on sale for around $20 clearance. We hate them. They are hard to put on and the snuggness makes them squeeze air space out of our smartwool socks causing feet to get cold. Larger sizes should help that. We have found that Crocs over the smartwool socks/booties built into the drysuit are perfect. Easy to put on/take off, comfortable, and clean and dry very fast.
Mine has the latex neck gasket which takes some getting used to. They make a version with a neoprene soft gasket that is not quite as waterproof if you fall in but much easier to used to
We use the Kokatat Lightweight Paddling Suit which has the neoprene neck gasket. When we bought these last year, I wollowed around in 39 degree water (while wearing a PFD) for about half an hour to test it and I never managed to get my neckline low enough to get my neck wet the setup is so bouyant. In rough enough water, I'm sure it would start trickling in, but that's a price I'm willing to pay for the comfort.