For L.A., the sunroof is a take it or leave it kind of deal. I have a fully loaded Ti Lusso. The sunroof looks great from the outside, but it actually only opens up maybe a foot? The privacy cover is also semi-translucent, which can let heat in. Since you live in L.A. with it's killer summers, the all-black glass sunroof is going to get very hot. If it was me and I was ordering the car, I'd skip the sunroof. Not having the sunroof also has a performance advantage as it removes the weight of all that. That weight is also in the worst possible place for performance which is the top of the car.
For performance, get the Ti Performance package and the High Performance Bi-Xenon headlights. The Ti Sport already has all the aero pieces. If you're ordering it, the leather interior package is well worth it; the smell of the Italian leather alone is worth it, not to mention the beauty it adds to the interior.
I believe the sport package includes 19" wheels. In my opinion which I know is in the minority, I think the car looks best with 18" wheels. I'm actually running 17" light-weight wheels I bought aftermarket for the weight reduction. They look great, although the 18's would look better if that's a critical issue for you. The 17's I bought weigh 6.5 lbs less each than the factory 18's, which is a huge amount of weight to remove in a critical area. This improves the car's acceleration, braking and cornering. It also improves the ride because of the increase in tire sidewall. They do come in 18" size, however the 18's were 2 lbs heavier which is why I chose the 17's, but visually I'll acknowledge the 18's would look better. I chose performance since I don't see the wheels when I'm driving. The other advantage of 17's or 18's compared to the 19's, besides more tire sidewall and lighter weight, is the tires are cheaper.
The HK sound system is okay. Some think it isn't compared to whatever they think is better, but I think it sounds okay. I don't listen to it much though. Would I have ordered it? Probably not. My car was one they had on the lot, so it came with it.
The driver assist package(s) I think are worth it for a couple of reasons. One, they do add safety features which can be beneficial, and Two, insurance. Your insurance will be cheaper if you have the safety packages.
The cost of the sunroof and HK sound system is almost $2,500. By not getting those options, you could spend that money on getting Eurocompulsion's V2 intake and Phase 1 tune which will do MUCH more for you than the sunroof or the HK system. The intake and tune combined are less than $2,000 and transform the car's performance like magic. You can add an aftermarket exhaust if you don't mind the extra noise, and gain a bit more performance (maybe another 10 hp), but those will run you anywhere from $1k-$3k depending on which one you get.
The Giulia is an amazing car; you'll love it.