Depending on your budget you can spend big $$$. I have had great luck with Coleman. I own 4 and all do what I need. I have had to seal the seams but thats about it. They may be less in cost but price doesn't always get you what you think. Others will have different opinions of course.
If you have a Sam's club near you, I would check there periodically. They usually have one model thats a pretty good size and as the end of season approaches it gets discounted significantly. Also, you might have some luck through Craig's list.
We got ours from Sams. I am not sure that will find a better deal out there for the money. I would try Walmart too but I know that Sam's has a good selection of big tents that would be suitable for you whole family.
My (lotsa) rules for tents (your rules may differ).
1. Don't get cheap. The money you spend buying a tent every time the fabric tears, the zipper or pole breaks and you would spend more money than if you got a good tent in the first place.
2. Don't forget to consider a groundcloth (aka footprint) to protect the bottom.
3. The fly should cover AS MUCH of the walls of the tent as possible. This provides not only an insulation layer and strength but keeps you drier for when you need it.
4. Freestanding! A staked down tent cannot be picked up and shaken clean - a vacuum cleaner isn't practical and sweeping is a pain and never gets everything out anyway. This also helps when trying to setup a tent on hard ground. With some extra lightweight rope you might be able to lash the tent in place and this is much more difficult with a stake down tent.
5. New stakes - whatever the price of the tent they always seem to stock it with the chintziest pieces of metal that bend or can't be nailed into hard ground in the first place. You cannot guaranteed the best ground for any tent and it's good to replace the stakes with better ones.
6. If you can't set it up right there in the store, don't buy it. Most people that do that resolve to liking their tent and all its shortcomings rather than walk away and use or buy a tent that they liked. It's what you can't see or experience that means you settle for what you get, unless you buy at a place that has a great return policy. I meet campers like this all the time.
7. Set it up and break it down several times before using it and before you start pay close attention to how it's packed. You never know what the weather or lighting conditions will be like and you want to be as familiar as you can. I have set up my tents in rain, snow and dark with ease because of this.
8. Warranties are good but there are some good ones and some bad ones. Some will say, "Of course we'll fix it, but you pay the shipping both ways to our factory in Mongolia". Many new tents are sold because of this, rather than trying to use the warranty. Some brands (like North Face) you can take to the retailer (REI for example) and no questions asked, they'll just hand you a new replacement.
9. Features - Does it have or do you need a loft, vestibule, ceiling clips, or storage pockets? Does it have or do you need solid walls or screened walls (privacy, strength and weight differences) and this helps decide keeping the fly on or off but not give the neighbors a free show (important for most females that I know of). How many poles and how difficult are they to identify and install. The better the pole configuration the better the tent stands up in a strong wind.
10. How much can I put in the tent, really? When a tent describes how many it sleeps, it assumes NO GEAR and that everyone is skinny as a rail and no more than 5'10" by 18" wide and always lie down straight as a rail. You will need to save room for some gear (especially in inclement weather), is there enough room to contort and change clothing without chasing everyone out (especially in inclement weather), can you sleep in your favorite fetal position and what about pets?
That picture attachment in another post shows a great tent and it is similar to the ones I like and own. It I want cooler, I loosen or remove the fly. The vestibule allows for emergency cooking in bad weather. I usually set up a separate tarp away from the tent to prevent fire damage, but it's up to you.
We've always had pretty good luck with the Coleman tents. I think that everything is probably made overseas anymore. If you go out quite a bit I would suggest spending a little more money. A tent is shelter and that's the main thing. I think the specialty stores such as Cabela's or Gander Mtn probably have some good quality stuff.
+1 for Art.
Specially about that... you get what you pay for. A good manufactured tent can last a very long time with proper care. Check the Kelty lineup of family tents; the Mantra 7 used to be a good one, but I think they don build it anymore.
Another suggestion - if you're going to spend the money to get a large tent, get an even larger tarp and always hang the tarp over it. A tent that never sees rain or sunlight will last a LONG time. I have a cabin tent that's 21 years old and is still in good condition.