I think the most I have ever spent on a 24-48h layover was $500 or so and that was Venice, bought dinner for me and both F/Os, and some purses for my wife and I hit up the grocery store.

If I'm on a Greenslip, I eat well and pay for dinner if the other guy comes. Any flight with a guy on probation, I buy dinner/beers/coffee depending on schedule.

Even then it's really hard to envision needing a budgeting app for layovers.

Normal domestic layover. Get to hotel, gym, go eat $20-40 depending on the place. Maybe $50 if I have beers. Next morning $5 coffee, and that's it. I'm not spending crazy cash on entertainment on the regular.

I did see Iron Maiden in Mexico City and that was maybe $100 including beers at the show.

Couple of times when my layover was where a race was (I bid around the Supercross schedule) I've spent $50 if the other pilot wanted to come to the race for an industry guest credential.

Not really sure what entertainment you'd be spending baller cash on.

I do have a friend who tried to go to every club mentioned in Motley Crüe's "Girls Girls Girls" if he has a layover where one is. That could be a money pit.