How do you usually deal with keys for a steam bundle?

Do you just choose the base game and then specify that it's the complete edition in the description, or do you do something else?

Yes. It's simple, it works, and the winner doesn't own the base game either, so they get the maximum one can get out of the key.

I mostly buy keys from bundles, so whenever I'm listing a giveaway I'll first find the bundle discussion here on SG and copy the AppID. Then when I'm creating the giveaway, in the game search bar, I use the AppID instead of the game name. That ensures I'm picking the right edition.

If I were to buy the key from a store and wasn't sure which AppID it referred to, I'd probably spend some time on SteamDB looking at the different AppIDs and trying to determine which one was applicable to the key I got. Let me know if anything in my post sounds unclear and I can try to provide more info and/or screenshots of what I meant