Enter my sewing machine and about 30 minutes of my time!
This project is easy enough for anyone with basic sewing skills and a basic sewing machine. I'm sure a serger would make it even easier, but I only have a regular machine and it was no problem at all.
So first I put the mattress pad on the bed inside out (yeah, it's kind of pilly on the underside). Then I lined up the corners and pinned the excess. I went about a foot away from the end so I'd stay away from the more complex corners and be able to do just a straight seam.
Then I did the same with the bottom/fitted sheet, clearly I'm not one of the tidy housekeeping types that irons her sheets:
Then I just did a straight seam across the whole thing, including the sides. After that I cut the excess off: on the sheet I used a pinking shears, but on the pad I used the pinking shears just on the thinner side panels and used a straight shears on the fluffy stuff.
Yes, I used black thread because that was what was in my machine, I'm lazy like that. I knew it wouldn't be visible when done anyway.
In making the bed I put the seams at the top so they'll be under our pillows and not a bump at our feet to annoy us. Actually, the mattress pad bump is not nearly as big as I thought it would be!
So just like that we have better fitting bedding!
Oh, and I decided to leave the top sheet the normal length since we can just tuck the extra in or fold it over at the top.