Is this a pleasant town for one night stopover?
If not, where within 30miles?
Ellensburg is OK. The college campus is nice and there are some fairly good restaurants in town. The Yakima Canyon just south of Ellensburg is a nice day-drive.
Depends where you are coming from and going to. Not much else along I-90 within 30-miles.
Yakima 30 miles or so south of Ellensburg, but south may not be where you are headed. Think I would pick Ellensburg over Yakima.