The max depth in Willow is 55 ffw. Most of the attractions are in the 40-45 foot range. As far as water temps, I dive dry so I usually don't look at the temp gauge often. Surface temps are in the 70's. I think we are in the upper 50's at depth. Funny we get a bunch of divers that drive up for the warm water. LOL
Crowds......LMAO.....Ok, the big crowd is Thursady night, it is when our local divers meet for dinner and diving....maybe about 20 of us. Last Sunday for example there were a total of 10 divers. There are different areas, so I only saw one group of divers at a picnic table eating lunch and saw no one while under water. In fact I have never seen another diver besides my buddy while submerged at Willow....ever unlike Dutch where you almost have to wait in line to see something. They have a sectioned off swimming area and on a hot day there may be 200 swimmers, but they are not even near the camping or scuba areas.
The place is VERY laid back, basically you pay to get in and you are on your own. They don't have anyone watching you or telling you what you can or can not do. You can dive at 3:00am if you want! Of course you can only get air fills during regular business hours, so plan accordingly.
FYI :
Make a right out of the parking lot and follow the road to the traffic light. Make a right (RT 422 East) and follow it down for a few miles, there will me a McDeath's on the right side and a small supermarket and drug store across the street..
When you decide for sure, let me know and we'll meet up. My wife also dives, so it may be a nice treat for your wife to have a fellow woman diver there.