I'd probably go with two tents, a one-person and a two-person, because it gives you more flexibility. If any of you want to take a solo trip, you take the one person (this would be you, or maybe your older son, for now.) If only one of the boys can go, you can take the two-person tent (this might be you and your younger son - I know that as my son started driving and got older, his own life took up more of his time, and our trips got fewer.)

It also gives you a little more flexibility on campsites. With a three-person tent, you've got to have a clear, hopefully flat, space big enough for the whole tent - that can be a little hard to find sometimes. However, it's usually easy to find a spot that has a couple flat spots that would fit a smaller tent.

I sent you a PM (private mail) with a couple of other thoughts; it's that little flashing envelope at the top of the forum. Just click on it (or on the little pointer by My Stuff, then select "messages.")