I really appreciate all the advice (and I'm glad to see I'm not the only one who gets frustrated with her spouse!)
UPDATE: We went to the gaming thing yesterday. It turns out we packed our character sheets somewhere we could find them, which means of course they were nowhere to be found. I called our GM friend ahead and he had some blank sheets there for us, so I was pretty much able to recreate my character from memory (since I had already emailed the story, I just had to pick the numbers to fit). DH pretty much started a new character, but presented a choice to the GM: I'm thinking of doing this way or that way, which would be easier with what you had planned? So that's pretty much taken care of, I had a blast, and I'm really looking forward to next week.
The cleaning thing is less cheerful, but at least something happened. Basically, I decided that since I have been cleaning and packing non-stop for the last 3 weeks, and DH wanted to leave everything until the last minute, I am now officially "moved" and anything left in the old house is his problem. DH has been really helpful the last three days or so, but not much before that, so not surprisingly, there is still a bunch of junk left.
In-laws had someone coming to put in new carpet this morning (we were supposed to be out as of last night) and someone else coming to look at the house around noon, so at least DH realized this was a real deadline. I did go over to the old house with him last night around 11:00 (when we finally had time after other commitments), but I basically loaded up my car with the easy-to-pack stuff and came home to go to bed after about half an hour. DH got home at 3:30 AM, having cleaned most of it (I think), but still had a bunch of stuff left. He moved it all into the kitchen and the laundry room so it wasn't on the carpet, but I'm sure my in-laws aren't thrilled about showing the house to a prospective renter while there is still junk in two of the rooms.
As predicted, MIL is upset and FIL is making excuses for DH. We're having them both over for dinner tonight, then MIL and I will hang out (probably unpacking) at the new house, while FIL and DH go back to the old house and finish up. FIL just had surgery on his foot, so he's not supposed to carry anything - at least DH knows this, so he'll still be doing most of the work. I told both MIL and DH that I am done with the old house, and if my in-laws aren't satisfied with its current state, to talk to DH about it. I feel really bad doing that, but this is one of the few times I have any leverage to make DH follow up on his procrastination promises. Plus MIL already knows how frustrated I am about this personality trait of DH's, so I think she understands the deeper reason.
I really do appreciate all the advice on here - reading that linked article, I see a lot of me and DH in it. He's not the complete slob the article talks about, but he certainly has his own time frame for things (he completely blows off my deadlines) and apparently "eventually" is a valid time frame for him. Right now I just want to take two weeks off my job to unpack and unstress, but I can't do that :-(