hybrid bicycle for a big guy?

FIrst, good for you!
Second, a good bike shop will be able to give you the best advice on what bikes to try, the size that works for you and will be there for you when you have questions about mechanical issues or want to find good places and/or people to ride with.
I find bike shops and their employees are usually quite accommodating.
Start out slowly and keep the biking enjoyable and everything can easily fall into place for you at that point.