My dd is just 4, and for the last year or so has enjoyed Hungry Hippos, a 3-d farmyard game based on Beetle, and magnetic fishing games, and over the last six months has really started to enjoy Ludo and Snakes and Ladders.
None of them are very interesting for the adults, but dd loves them.
Another for shopping list and tummy ache. Operation they love but they want it to beep, not the other way round. But it is a NIGHTMARE to clear up afterwards - I have chucked most of the money and cards away.
Collision, I have got my various Orchard Toy games from shops such as John Lewis and Fenwicks. I think I found Cockadoodle Moo in a National Trust shop but have seen it in some mail order catalogues too. We also have Tumbling Monkeys (which was a handme down from friends. It's very popular too although they do need help setting it up. I'm pretty sure I've seen it in Woolworths & Toys R Us. There is another similar game with bees which I think came from the Early Learning Centre. Hope that helps.
My almost 4 yr old currently loves You Who from the ELC - it was actually one of his older sister's Christmas presents. It is a fairly simple game without lots of small pieces to pick up. Involves asking lots of questions to try to guess which card the oppopnent has. I think other stores do similar games at lower cost. I don't mind playing it with him and normally I find these things fairly tedious so i suppose that's some sort of recommendation! He also likes snakes and ladders.