Gym training is awesome. Freedom of the Hills, if you haven't already memorized it. Mark Twight recommended framing houses. Build some multidirectional anchors. Do a hanging belay at the gym. Breathing and balance work. It is possible to use crampons and axes on trees, if you have a beater tree that will not cause problems to hack up. You could practice self-rescue, using your prussiks, pulleys and hauling. Setting up your bivy blindfolded. Basic meteorology. Basic avalanche avoidance. River crossings. Medical stuff. Cooking tricks. Climbing in boots, chalkless, gloved even. Navigation and routefinding in inclement weather. Figure out what bars you can tolerate.
Guides can help you gain skills very quickly. As long as the other clients are not a drag.
Often you hear people go from Shasta to Rainier to Denali.
The Eastern Sierra is a great place because Highway 395 makes it so accessible. Awesome granite, very small glaciers, plenty of lakes and great weather, generally.
You could start there and go north.
There are clubs and groups too. Mazamas.org is out of Portland. Traditional Mountaineering web site has some nuggets, and are based in the NW. Summitpost, telemarktips, etc are message boards you can hook up with people. There's a few more too.
Think if you will need new boots and break them in by what date. Consider aftermarket liners for double boots. A tune-up of laces and footbeds and socks. Retreat with non-petroleum waterproofing. I have heard of people being contented in leather boots on Rainier. Possibly 2 pair socks or overboots? Laminate a piece of foil under your footbeds for cold conditions? Carry a spare bottle cap for your platy for when your hose freezes. Not sure what season you are going. Helmet? Goggles? Favorite chemical water treatment? Happy with your headlamp?
Link to Twight Book