Steve:
Steve takes you back to your apartment. Unlike his apartment, yours isn't under S.H.I.E.L.D.'s radar yet so you both go back there when you need to get away from everything. You both lay side-by-side on your bed and rant about whatever's been bothering you, and eventually you both fall asleep.
Bucky:
One of your best friends owns a dive bar in the city, and they gave you a key. Sometimes during the day, when its empty, you take Bucky there and you guys sit up in what's usually the VIP area. You let your feet hang over the edge and stare down at the stage while you swap stories about childhood memories.
Pietro:
There's this semi-abandoned lab in the Avengers tower. Some of Tony's equipment is still there but no one ever goes in there, except you and Pietro. If one of you ever wants to meet there you text the other a microscope emoji and then you each silently slip away and head there separately.
Loki:
A beautiful island on Asgard. It's not big enough for anything substantial to be put there, but it's the perfect romantic getaway for you and Loki. You two lay down on the beach and watch the sunset, then spend the night staring at the stars talking about nothing and everything.
Clint:
There's a skyscraper that Clint used to hang out on top of, and he even put together a little garden up there. He also brought a chair up there for himself, and now he's put a second one up there for you, so that both have a quiet get away above the rest of the world.
Thor:
A park just outside the city. You're not actually alone because there are a very few other people there, but it's away from the people you know so it's peaceful. You guys sit at the base of a willow tree in the park and sometimes you have a picnic or you'll bring a book and read to him.
Tony:
Balcony of the Avengers tower. Tony makes sure that no one can get to that floor, so that you two can be alone. Then he sets up a picnic blanket with some food, wine, and candles. It's incredibly romantic and the view of New York at night makes it even more perfect.
Natasha:
Nat found this little whole in the wall cafe in a small farm town in the middle of nowhere a while back. She takes you there sometimes, it's pretty much the only place you guys can go on an actual date. Your also pretty sure all the people that are there when you go are S.H.I.E.L.D. agents. Your also not truly sure where it is, Nat flies you there and makes you sit in the back of the quin jet.
Wanda:
After the first time that you built a fort in your living room for the two of you, it became a regular thing. Now whenever you need a romantic night alone you guys put up the blankets and block out the world to watch movies.