Sorry for your loss Mazinga. I had the same thing happen to me about 9 years ago when I lived in an apt. Luckily I had State Farm and got everything replaced in 3 days (actually went to Circuit City and they had everything packed up and ready to go for me). State Farm was pretty pissed because I've always kept my receipts for anything I've purchased over $10 (faxed them over like 100 DVD receipts which they were trying to screw me over "moneywise" for and 50 others). Replaced all my electronics and cut me check for the DVDs. Your RI company will initially try to low-ball you, so be careful (and have receipts ready). Some companies even take pictures of your stolen items. Just make sure everything which was stolen was on the police report.
More than likely it was either maintenance, neighbors or believe it or not, friends. Neighborhood kids are notorious for B&E (cars, apts, etc). Still, breaking into someone's apt is pretty risky in this day and age (they could catch a bullet/they don't know if you have an alarm system, etc), so it was definitely someone who knew your schedule, your apt. and definitely knew you or anyone else wouldn't be there. Neighbors always come mind (who's to say you just didn't go for a bite to eat or a quick run somewhere). If they dropped a duece, they knew your schedule and knew you weren't coming back anytime soon (friends or acquaintances who've been at your home recently). Just trace back: Did you get a call that day from anyone while at work? Did anyone call your home phone that day, etc).
Ask anyone if they saw anything and you might find out who did this (you'd be surprised how noisy people are and kicking in a door or window makes a lot of noise). Also, if some things were of "personal/emotional significance" to you, you might want to check Pawn Shops within a 10 mile radius of where you live. If you see something of yours there, report it to the cops (don't tell the Pawn Shop or by time the cops get there, your stuff might disappear).
Last, once you file a claim and receive the money/items most companies will not let you file another claim for almost 2-3 years. Get an alarm installed. I ran across this when I tried to get Home Owners Insurance through State Farm when I bought my house. They rejected me at first, then when I called to cancel my coverage with them (I have about 10 things covered: everything from cars, wedding ring to my video game consoles), they changed their mind and approved me. *ssholes!!