How did we get from a 3pm check-in to a 5 or 6pm meeting?  Check-in at 3pm and schedule the lady to meet you at 3:30.

As others have said, early check-in is a very good possibility but seldom guaranteed. Unless you know the gal and there is some flexibility in her schedule I wouldn't assume that you will be able to get into the room early.

Looking to hook up with a provider who does out all only.  Since I'm approx. 2 hours away and want to arrange a daytime encounter, how do you book the hotel?  Most hotels have. 3:00 pm check-in time, so if I check in after 3, then call the girl, more than likely it would be at least 5-6 pm.  Put the appointment and drive time back into the mix, and I'm looking at getting back between 9-10.  That would raise a red flag with my significant other.  But, I don't see any other way unless someone has another suggestion.

A lot of higher end hotels allow early check in I've done it while on vacation. Just call the hotel and check. Most will let you take the room around noon.

Early-check in is an option if the hotel has any available rooms you can check in early.
You could make up a story say you have been traveling and really tired is there anything available before check-in.As long as there is not a major event in town where hotels are already booked up you should not have a problem.If for some reason you cannot check-in until 3pm let the provider know you are shooting for an earlier time but if not the appt would be at 3pm.That way if you have to wait to check-in she is there at 3 have fun for an hour or two and you are back on the road by 5.

I think you have it backwards. Set the day/time with the girl first a few days in advance, THEN get the hotel. I do 4 pm for sometimes the room isnt ready right at 3 pm either and 4 gives you a buffer zone. See the girl from 4-6. Other option I use is a morning appt. Check in to hotel on way home from work but then go home. See the girl the next morning at 8 am or 9 am, or later since check out time in usually noon. Many times I'll do 9:30 to 11:30, ask for late check out in case shes running late, then we go out to lunch off the clock. DONT rely on early check in. They dont guarantee it and many times its not available and you wont know till the day of. Avoid that like the plague.

do not sell out on a Sunday night. That should give you the best opportunity for the early check-in scenerio.

You can try booking the room from whatever time you'd get there in the AM till whatever time you'd be leaving in the PM, especially if the time you give up the room is before the normal cleanning staff leaves.

You are on a business trip, will be driving all night, need a room to take a nap in and shower brfore your early evening appointment.  Course you'll pay the full rate for the room.

Works easier if the room is near a major airport, arrive early in AM from all night flight; catch an early evening flight out.