i can't be the only person who knows about the stickers...
Every time I mention this to people, they look at me like I've given them seeds to a money tree or some such desirable thing.
So, when you go to Starbucks and are getting hot drinks for a bunch of people, invariably the drinks spill when you are driving along. This is also the case for single drinks, if you happen to have a lot of speedbumps along your route. You get the point: the lids have holes in them, foam and what not often comes out of them.
ASK FOR A STICKER.
Really. Just ask them for a sticker, which will result in a coffee label sticker or a freshness-day sticker some other sticky-backed paper which you can then very carefully fold over the hole in the lid, thus preventing liquid from spilling out.
This will work for any coffeeshop that uses stickers in their store, and if it doesn't, then you have a lame and non-sharing coffeeshop and should find another one.