I'm wondering how closely they monitor the lenght of stay your car is parked.

Lets say I drop my car off at Ballys valet and leave it there for 2-3 weeks, maybe a month, whats the outcome?

I think it varies by hotel. But I know people that have valeted car for 3 weeks + but they were also staying at hotel

I've left my car at MGM for 3-4 weeks before twice now when I've traveled internationally. Just left it at valet, took a cab to airport and it's there when I get back. They never said a word to me I just left em like $20 told them I'd be back in a few weeks

There's a long thread about this exact topic around here, lots of opinions. Look for that one.

Can't vouch for anything longer than 10 days, but it is a good option. Please tip a little extra too. Maybe $5 when you drop it off and $5 when you pick it up after a week or two.