Truck camping, backpacking, ultralight mountaineering? What ya using it for? When you say 3 people, are you expecting 3 burly mountain men with full packs in the vestibule or you and your kids with most of the stuff in the Cruiser?
From your description I don't think your current Sierra Designs is a 4 season tent. Maybe an extended 3 season, but you would not be complaining about heat retention in a 4 season tent, they are usually too hot around here in the summer even with the windows open.
Do you have a target budget? A true 4 season, 3 man tent is going to be heavy and expensive. They are made to take punishment of winds in the winter.
I've always like Hilleberg and Bibler/Black Diamond, but they ain't cheap. Big Agnes, Mountain Hardware, Marmot, Nemo, MSR, some of the North Face all make fine tents. Eureka and Sierra Designs still make tents, too. Sort of define your requirements, size, weight, price and shop around.
In general, the Mountain Hardware Trango (probably what I'd buy if paying full price) and EV2 are sort of go-to 4 season tents. Not necessarily the strongest, lightest, cheapest but a baseline anyway.
Anyway, saw this over at Sierra Trading Post the other day. Nemo Alti Storm, not a bad tent and really a good deal at that price:
A Black Diamond Squall, no experience but the reviews aren't stellar:
Also maybe check out http://www.moosejaw.com
, REI, etc. to see what's available. If you find a brand & model that you want, don't forget to check Amazon, they'll probably be the best price.
If I was you I'd check Wilderness Exchange downtown or Boulder Seasoned Exchange & Boulder Sports Recycler to see what they have on consignment. If your time frame isn't immediate (and unless you're planning a climbing trip to the Andes or New Zealand I'm guessing it's not), their stock rotates and eventually they'll have something.