Lords of the Expanse/Player's Guide to Tapani

I'm putting these two together as a single thread, because they really do go together. Player's Guide has a lot of the same information, but only what players might conceivablly need.
Lords of the Expanse is the box set to get if you want the noble houses and court politics of high-society in your game. A large portion of it defines the various houses, their goals, policies, history, etc. There's everything from paparatzi to meddling aunts determined to make any noble PC start doing "something worthwile" with their time. Covers ways to prevent players from abusing social priviledge or noble title and covers the obligations that go with it.
House Mecetti and Malantha characters make very handy non-imperial villains.
While non of the information in these conforms to any litterary source I'm aware of (maybe one of the comics? Maybe it was used later by other authors?), it is still very helpful background, even if it is never used. And "Instand Adventures 2: The Tapani Sector" has several adventures that take advantage of the setting.
Are these essential: no.
Availability: you should be able to pick them up for a decent price on ebay or amazon
Usefulness: highly
Features: structure of 8 houses, politics, character templates, introduction of "lightfoil" (cheap, mass-produced lightsabre that does less damage (only 3D instead of 5D) and is prone to malfunction (1 on wild-die = shutoff) that is otherwise exactly the same and can be used by jedi), several adventure hooks and plot suggestions. Very little of the information is reprinted from earlier volumes--almost all new stuff.
Liabilities: short production run at the end of WEG means supplies may be limited.
D20 conversion: even if you don't use the stats and such, the information is still good.