We could ...
We could eat spaghetti / eat dinner.
Let's ...
Let's make a cake! / Let's bake a cake! / Let's bake!
Let's ...!
Let's go on a trip! / Let's travel!
Why don't we ...?
Why don't we play video games?
Why don't we ...?
Why don't we go running?
How about ...?
How about going shopping?
Why don't we ...?
Why don't we swim in the ocean?
Do you fancy ...?
Do you fancy dancing with me?