1911 .45's are a classic design. My wife has her eye on a Colt 1991A1 or similar, whenever she can spare the $$$ to get one. (Kimbers and such are great guns, but she likes the horse logo, so it has to be a Colt). She currently shoots a Glock 26 9mm.
As far as a handgun for defensive purposes, your P99 is an EXCELLENT choice. FWIW, I'd consider any firearm chambered for 9mm Luger (aka 9x19mm or 9mm Parabellum) or larger to be entirely sufficient for self-defense,
given the right ammunition. IMHO, a 9mm using hot JHP's--jacketed hollowpoints, for non-gunnies--is as good as a .45 with JHP's. So is a .40 S&W with good JHP's. 9mm's and .40's generally have higher capacities, since the smaller rounds allow reasonably-sized double-column magazines (except you're limited to only 10 rounds in California); or, a single-column 9mm or .40 will be thinner through the grip area than a .45, a plus for those with small hands.
My personal handgun is a Smith & Wesson 3913 LadySmith, caliber 9x19mm. It's a single-stack (8-round magazine plus 1 in chamber), highly accurate, very portable, and the workmanship is first-rate. My wife's Glock is a subcompact with a double-column magazine, so a 10-round magazine fits flush with the stubby grip, and around the house she loads it with a full-length 15-round magazine from a Glock 19. I load mine with Cor-Bon +P 115-grain JHP's, since I'm limited to only 9 rounds; my wife is less comfortable with the increased blast and recoil of +P/+P+ ammunition, so she sticks with standard-pressure Federal Hydra-Shok 124-grain JHP's, but she has 15 of 'em. :)
As far as AR-15 type rifles--if you don't mind the small caliber, they are IMHO the best civilian rifles in the world, and it is with good reason that they are among the most popular civilian target and defensive rifles in the United States, bar none. As far as brand preference, I'd highly recommend Rock River Arms, followed closely by Bushmaster, and I have also shot a DPMS. Finances permitting, I have my eye on a Rock River CAR Elite A4 someday.
The bad news--you aren't allowed to have any AR-15 type rifle in California, unless you either owned it prior to the enactment of your state's Protruding Handgrip Ban in the early 1990's, or go with a California-specific lower receiver that
cannot accept detachable magazines. (No, I'm not kidding. I wish I were.) Possession of a post-ban AR-15 in California is a felony, and IIRC the minimum prison sentence for mere possession of one is higher than the minimum sentence for rape.
In California, your options for a small-caliber, self-loading, detachable-magazine-fed rifle in .223 Remington/5.56x45mm are pretty much limited to the Kel-Tec SU-16 or a Ruger mini-14 with an 1800's style straight stock. Neither gun is as accurate or as durable as an AR-15 type rifle. If you step up to .308 Winchester, the Springfield Armory M1A and derivatives, particularly the 16" barreled SOCOM series rifles, are very appealing, and well thought of. SKS's with fixed magazines are also legal in California, and are very economical ($200 or less for a Yugoslavian variant, I'd expect). Or, if you really like the look, feel, and accuracy of the AR-15 type rifles, look into a California-specific lower receiver such as a FAB-10.
Here's our current collection:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=364x1689245#1690884