I think Lucas is going to outgrow his Graco Snugride soon. I have been in denial about having to research and buy convertible car seats. Tell me about the one you have, how it fits in your car, etc. We do not have the $$$ to buy 3 Britax seats but of course we want to get the safest we can!
Re: ok, tell me about your convertible car seats
We use the Evenflo Triumph Advance for DD1, and I love it. It's somewhat bulky, but that's ok in the minivan. It's easy to tighten correctly, which is what I love most.
We also use Alpha Omega Elites, and I hate them. The straps continuously get caught behind the seat in the mechanism, and it's a pain to tighten right.
We bought the Evenflo Momentum 65 DLX seats. I replied to another post the other day about how much I love them : ) Our 2yo is also in an Evenflo Triumph and we love all 3 of them.
For us, it was between the Momentum and the Safety 1st Air Protect because they had the most side crash head cushioning. We tried both out at BRU (they let you try them in your car), and the Air Protect one did not fit rear facing at all in the captain's chairs in our minivan (we wanted to try it because a lot of reviews online mentioned it being a problem). The Momentum fit great rear-facing. It is a wide seat though, so it wouldn't fit 3 across if that's what you need.
Anyway, I would suggest looking at them in the store and seeing how they work for you. The Momentum DLX version has SureLatch connectors which are SO easy to use. Once the latch is connected, you just push down on the seat the the straps automatically tighten for you!