I really love it when a parcel arrives, spending time having a lookie through and then choosing seeds I want to add in. Then a mad rush to the post office to get it back on its way the same day if poss.
The send your seeds in and they get sent back swap is good, exciting to have a total mystery, but I think it misses out on a little of the fun. They also seem to be specific, squash or tomatoes rather than all veg. You don't always know what you want until the choice is in front of you, it may be a case of just taking 2 or 3 seeds to try.