When PCS'ing to a new installation, my first concern was always the commute. Arriving at work before first light, multiple trips back and forth to post, and being close to the unit for recalls and trips to the barracks is a big consideration and has a huge impact on quality time versus travel time.
Fort Lewis straddles Interstate 5 just south of Tacoma and North of Olympia Washington. The portion of the installation that is south and east of the freeway is considered as main post, to the north and west of the freeway is north fort. The installation headquarters, main PX, Madigan AMC and numerous other troop units occupy main post. North fort is well known by ROTC Cadets; the barracks used for ROTC until recently were wooden "WW II" barracks located on north Fort Lewis. In the past five years, many new barracks and unit area construction projects have been completed, and others are underway.
When I moved to Fort Lewis, friends and associates who had been stationed here before recommended that I look for housing to the south, in the Lacey or Olympia area. The biggest quantifiable reason I was given was the commute. Traffic from Thurston County is significantly less than that from Pierce county and Tacoma. Additionally, many people feel that crime is less of an issue in Thurston County, which is much more rural than Pierce.
Another area that has become very popular, especially for those who will be working on main post, is Yelm and Roy. Located several miles from the back or "East" gate, Roy (in Pierce County) and Yelm (just south of the Thurston County line) are very convenient commutes. Although both are small agricultural communities, Yelm is the fastest growing small town in the state; primarily because prices are somewhat lower than those in the larger towns on the freeway. If you think you will be working on north fort, Yelm and Roy may not be very good choices; the only route is across main post, and under the freeway at one of two points...always a traffic jam.
To the north are the Pierce County communities. Lakewood is almost right outside of the gate, just a short distance north on the freeway. Not a bad commute, with traffic concerns only during rush hour. Further north is Tacoma, Graham, Puyallup and other small communities and neighborhoods. If you are into being in or near a large city you will most likely want to go south.