You have a few choices...
Alderwood RV Resort (www.alderwoodrv.com
) is on the north end of town on the Newport Hwy. Very nice place. Big Rig friendly.
If you're a member of the Elks, Lodge 228 is located in the central part of Spokane Valley and takes big rigs easily (east of central Spokane). Very easy on the budget too.
If you're eligible, there is a FamCamp out at Fairchild AFB (to the west). Very big rig friendly.
There is a Coast-to-Coast park in Cheney just to the southwest (Ponderosa Falls Resort). Trees. Fairly easy access to the interstate.
There is a large rv resort, Coeur d'Alene RV Resort just off the interstate in Post Falls to the east of Spokane. Very nice place and the interstate noise isn't too bad. Very big rig friendly.
There is Riverside State Park, which is almost downtown, but might be tough getting reservations and the big rig spots are limited.
There is KOA of Spokane in the eastern end of Spokane Valley. Do you like lots of trains? This is your place!!!
There are other campgrounds, but these are the ones I'm familiar enough with to make a recommendation.
The problem with Spokane is that it is easy to get from east to west, west to east on the interstate, but if your destination is to the north of the interstate, then traffic becomes an issue, because there is NO limited access north-south freeway in the city. They're building one, but it won't be done for some time yet. The main route north is US-2, also known as Division St., and yes, it will be stoplight-to-stoplight and slow. There are side street arterials, but you need to be familiar with the city to know which ones move and which ones peter out. I'd look for the campground on the side of town closest to where you need to be and go with that.
OH! Almost forgot. Make SURE you get down to Riverside Park in downtown Spokane and feed the garbage-eating goat. I won't say any more - you'll have to go see for yourself.
Spokane is a beautiful city in the spring. Enjoy!