My 2 girls are 6.8 and 8.8yrs old and they are really into arts and craft.
They still enjoy the following and plays with these most of the time.
Magnetixs, K'nex building stuff, Moonsand, Playdough, Hot Wire (building electrical items etc), sometimes even plays with their Happyland (I have 2 boxes so they can build a town etc, they still play with their duplo lego (2 boxes of those too), Polly Pocket, Ice Hocket table,lots of boxes of games and have recently in the summer been playing with Giggle Wiggle, Pirahna Panic, Pictureka, Jenga, HSM DanceMat, Monoploy, Battleships, Blopen and lots more others.
As the ages are quite close, they do play a lot together and still also do lots of crafting together like painting moulds of princess, mermaids, teddybears.
I have started their christmas shopping and I have got them the following: 2 boxes of lego (the smaller size) family house and apple house as I think its good for them to learn to read the instructions to build, 2 boxes of K'nex - the amusement series - again more building and learning stuff, the 8 year old wants to learn to knit so have bought the Fun with wool set - John Adams and they both have asked for the Wammy, the 6 year old has asked for more moulds so will get the Hello Kitty Rotator. With the moulds, I get lots of different types and also will get more plaster from Baker Ross so when they have used up all the plaster that came in the boxes, I just make up more moulds so they and their friends can paint them.
As they have a lot of toys already, have decided to buy more learning stuff rather than playing stuff.
Sorry its long, hope there are a few ideas out there.
Of course, there is also the DS and Wii for them to play with if they don't want to play together.