I can't do the Gap's, they aren't actually plus size enough for me. My favorite skinnys are Am Rag Cie from Macy's but I don't think they are current. They are technically jeggings but are structured like regular jeans. I rarely find plus size jeans that fit like true skinnys.
I also have the Old Navy Rockstar jeggings but I use those exclusively with boots and tunics. They vary WILDLY in sizing though. I have two pair in the same size, style and color--one fits great and the other can barely button.
I just got a pair of Kut from Kloth jeans that claim to be skinnys but are actually straight leg. I'm really liking them. They are the nicest denim I've ever had in my size.
I had a pair of NYDJ a few years ago that I was disappointed in. I haven't tried them recently but what I've seen on the racks has felt better so its good to hear that they have actually improved.