The thing is, with kids in the mix, you never really know what is coming next.
We're on our first RV, but here's what we have gone through so far.
Started w/ 2 kids, wanted something that would work with the '05 Suburban we already had. So we got the TT in my sig. Started taking longer trips (from SLC to West Coast) a few times a year, were unhappy w/ the 'Burb's towing performance on those long trips.
So we bought the 2500hd Duramax (towed like a dream), had another kid in the meantime, so the 'Max was full. Plan at the time was that we'd be looking at a larger TT or 5'er in the next year or so to accommodate the growing kids.
Meanwhile, the relatives with whom we liked to camp on the West Coast moved or had little kids and didn't want to camp anymore, so the last couple years found us leaving the TT at home and throwing in to rent a vacation house when all the family got together. So we've been back to "local" camping trips the last couple years -- haven't gone more than 3-4 hrs lately (fortunately for us here in Utah, "local" includes destinations like Moab, Arches, Canyonlands, Bryce Canyon, and Zion NPs, among other places that are only 4 hrs away, so we're not suffering for lack of destinations). Combine that with the older 2 kids being involved in soccer/dance/etc, our nights in the TT decreased in a big way last year.
With baby #4 on the way, making the 2500hd too small for 4 kids in seats, and the prospect of fewer long trips, we downsized our TV to another Suburban. We're out of TV options for a much bigger trailer that will (comfortably) haul a family of 6 around (no, a van is not an option, don't ask ...). So we're now likely looking at a class A or C MH w/ bunks as our next RV.
Just sayin', you never know. 3 years ago, we thought we'd be looking at something a lot different than we are actually looking at. When we bought the Duramax, we were weighing between buying the new diesel 1 ton on the expectation that "we'd have it forever," so might as well get one truck and keep it for 8-10 yrs. Glad we didn't drop $55k on a truck that we would have outgrown this year.
So my opinion is, buy what works for you now, and don't hamstring yourself to the point that you cannot make different decisions down the road if you want to. You never know in 3 years what you're gonna be wanting to do. Don't make it so you have little choice!