When we were there RVs and oversized vehicles were parked at the end of the casino farthest from the racetrack. The parking lot is hilly; it takes work to get level, but it can be done. There are islands of grass and some small trees that break up the openness of the lot, reducing through traffic and keeping speeds lower in the parking areas. Also made it easier to walk the dog. Some RVs were parked in the next lot closer to the casino and that seemed fine too.
A new parking lot is under construction on the outer side of the curved road, also near the back of the casino. Though still a work in progress as of June 2014, there was already a sign posted that it will be “Oversize Vehicle Parking - Buses, RV’s, Tractor Trailers”. This will only minimally change the distance to the casino, though it will then be necessary to cross the driveway to walk there. Doesn’t look like it will be any more level than the existing parking areas. Didn’t look like they planned to break it up with the grass islands.
The casino itself is laid out in the center of a round building. Slots and table games are in the center. Smoking and non-smoking sections have nothing to separate them, so even non-smoking is a little smokey.
There are restaurants and a couple of shops on the perimeter. Decent restaurants is what we like the most about Mohegan Sun. Ruth’s Chris Steakhouse was a standout for us; they have an awesome bistro menu if you eat in the bar/lounge. The shops are kinda negligible: casino-themed gifts; wine and cheese.