Heck, yes--I have only one lined skirt for winter, so I would be pretty much out of luck with skirts if I didn't wear slips. I also often wear them to smooth out knit or tricot skirts and dresses, and with sheer skirts in the summer.
I wear half slips for the most part. I have a variety, ranging from black straight short slips (one mid-thigh and one just over the knee) to a longer flared slip in nude (great with sheer summer skirts). I size up for comfort--a medium or large works great for me, although I am a size 6.
You can buy them at any department store or a place like TJ Maxx--they are also easy to find at thrift stores. Vanity Fair is a nice brand. Don't get misled by shapewear--the Spanx "slips" don't really serve the same purpose as a plain slip, especially with sheer skirts.
