Hummmmmm....well, maybe Lincoln City or Newport....possibly Astoria. I havent been there for a couple years, but Ive heard its the New Growth area for the Oregon coast.
I live in Coos Bay and love it here, but youre not going to find a whole lot of shopping. We have the standards, such as Safeway, Albertsons, Fred Meyers, BiMart, WalMart, plus several little unique places. There is a mall here, you can look up Pony Village Mall on the internet and see what stores we have.
Lincoln City has the advantage in shopping due to the outlet mall. YUMMMMMY! I do love that place.

But see, I just go up there 2x a year and spend a weekend w/friends. That way I get my shopping fix in plus a fun weekend. Its not a long trip up, only about 2hrs.

Or you can do the same time frame trip and go to Eugene. PLenty of shopping there.
But, again, if you dont want to do the drive and need easier/constant access,Lincoln City/Newport would be a good fit for you. I personally adore it there too. Beautiful area.
Astoria is so close to Seaside. Again, i havent been there in a few years, but it was great when I was last there. And as for tourists, well, the Astoria Seafood and Wine tasting festival is pretty huge, (well worth it too! IMO) and Ive heard about cruise ships going through there,.....maybe id best shut up now and let someone in Astoria help you out there. Seaside, look out during spring break! its THE place to go for the teen/young adult crowd during those weeks!
might want to spend some time in each town before you make a major move to the coast. See it during our rainy months too. Id recommend renting before buying (just like I would for ANY move, ANY where)
Best of luck to you!!
Tiffany