If I remember that location, it's fine. It looks scruffier than it is, but the area has been cleaning up every time I've been there. Just because of the distance, though, I'd say take a cab or the bus (There should be a bus line running straight to that shopping center from Market, either on 9th itself or one block over either side). Check out
www.sfmuni.com for maps of their transit system. Looking here:
http://transit.511.org/providers/maps/SF_712200711012.pdf
It looks like you can take the MUNI subway or streetcar to Civic Center, then switch to the #19 bus to go down 8th to Bryant, and when you're done, walk back the one block to 8th again and catch the same #19 bus back to Market Street (it turns around just a block or two past Bryant and comes back up 7th).
Even the Tenderloin isn't nearly so bad as it used to be. You're fine in the daytime even alone, and at night, it's ok if you're there together, so long as you stick to crowds and main streets. There's now half-million dollar condos in the Tenderloin.
While you're there, go out to the Castro and take a meal at Nirvana, this Tibetan/Nepalese restaurant on Castro street. Go early, because they get busy at dinnertime. If you're up for Tapas, there's a couple of famous places in the Mission district that are quite good - Ramblas is at 557 Valencia, and there's another really good one around the corner on 16th whose name escapes me at the moment. Take some time to wander the Mission district, up and down Valencia and some of the cross streets there - all kinds of neat funky boutiques and bookstores, the kinds of places San Francisco is famous for, but are disappearing from the better known neighborhoods because of rising rents.
Over in the Haight, there's Cha Cha Cha, a cuban restaurant, right near the panhandle of Golden Gate Park. Down in the Ferry Building at the foot of Market Street is the famous Slanted Door vietnamese restaurant. For Russian, try Katia's on 5th, at Balboa (Richmond District). A neat Italian place that's away from the tourist trap of North Beach is Vivande Porta Via (
Dead Link Removed, a longish walk back to Nob Hill, but the Fillmore is also very charming. Vivande has a dish on their menu I've heard about but never had the opportunity to try other places, because it's very time-consuming to make so many restaurants don't offer it. It's called Scrignere de Venere (literally, Venus' Treasure Box). Give it a try if you get over that way.