With the distance between Salt Lake and Seattle being around 832 miles, Baker City (464 miles) and La Grande (506 miles) both offer a close halfway point for the overall trip. Staying in Ontario (392 miles) would mean a shorter first day of travel, however, but depending how you want to break up the trip would be a viable option. Baker and La Grande are relatively small towns, but each offer some fine choices for stay and sights. As a resident of La Grande I may be a little biased to encourage a visit here, but I also visit close friends in Baker City at least twice a month and can promise equal treatment.
In Ontario the Clarion Inn is one of the only full-service hotels in the area. There is a great taproom nearby at Berts Growler Garage, as well as a range of local taquerias and pubs. In Baker City a popular place to stay is the Historic Geiser Grand Hotel, with close walking distance to a favorite local brewery Barley Browns. I also would highly recommend a quick stop for breakfast before you head north at the Lone Pine Cafe. In La Grande there is the recently opened Landing Hotel with accompanying Wine Down lounge and cafe. I would also recommend stopping in at Side A Brewing for a local pint and bite from the menu (I am a big fan of the fried chicken sandwich with its addition of pickled fennel). In each town there are of course a range of other places to stay and eat, including a selection of coffee shops, restaurants, taverns, drive-thru’s and bakeries to enjoy. Let me know if you have any questions, and best of luck on your travels!