Yeah I love black jack/Spanish 21 but it's too expensive these days. Like the cheapest tables are like $10 a hand out here. I go with them a couple times a year and we usually go for like 4-5 hours but like you I'm ready to leave after 2 or so.
I usually bring $100 for cards seeing you can be there 5 minutes or 5 hours with that amount depending on how things go and then another $100 for slots incase I'm done cards quickly.