suggests something cool and unique, like getting a coffee
Simple first dates (like getting a coffee, or a drink, or just walking around) are great because if you have a good time, you know you had a good time because you like the person! You didn't just have a good time doing a fun thing and the person was decent enough not to ruin it.
Especially in online dating, the first date is just supposed to be a "see if we're compatible" thing. The second date is when you get more complex. The third date is, if you haven't already, largely just an excuse to get inside of one of your houses.