We use the BD Megalight, and before this the Megamid. We started when the kids were 0 and 2 and they are now 7 and 9. We also purchased the floor and I sewed my own nest, but this was before the BD nest was available.
The floor IS heavy, but it's also VERY durable, not just in the long term, but also DURING a trip, when kids can be less careful than adults. This may become important on day 4 of constant rain.
Just a few things to counter John's claims. (No offense, and I have to say that the Shangri-La looks like a superb option.) In fact if I was purchasing, it may be my choice too today.
The Megalite is actually 96" X 96". I've also seen the measurements that John quotes on someone's site, but I think they refer to liveable space, ie a foot in from each edge. It's still smaller than the Golite though.
Yes, there is only one vent, but this has never been a problem.
I'm dubious about the thicker silnylon protecting from flying debris, but if it stretches less, this would be good.
The BD does have fixed loops, but if you untie these, loop them through the webbing three times and retie them, you have four instant lengths, depending on how many loops you peg through. The 8 extra loops would be reassuring, but I wonder how effective they are on a straight (not catenary) cut edge. John, can you report back on this?
Essentially the GoLite sounds like a bigger, heavier version of the BD. And I have to say the BD is a superb family setup. It's also fantastic for 1, 2, or 3 adults. Either of these tents will become immensely more versatile with an 8X10 silnylon tarp or 7X11 poncho out the front as an awning.
Good luck with it, and I look forward to a report and photos from both of you.