I went through this several weeks ago and was able to find several threads. Some key points to consider....
1) Go with CL2 rated cables so you are compliant with firecodes (assuming you are in the US or Canada)
2) IMHO brand name expensive cables are not worth the investment... I'm a big fan of monoprice
3) Try to minimize the number of bends in the conduit. If you do have to make a 90 degree turn its better to use two 45 degree turns with a bit of straight pipe in between. A chunky 20' long HDMI cable will be difficult to pull through a tight 90 degree bend. Definately go with conduit... a small investment today will save a tremendous headache in a few years when you are upgrading to a 4K (or 8K
) projector in a few years.
4) Protect the ends of your HDMI cables before fishing... use electric tape. Fishing lubricant can be very helpful.
5) I seem to recall that you should never run speaker wire AND/OR RCA cables (subwoofer) parellel AND within 1.5' of electrical cable. Any time your speaker or RCA cable has to be run past electrical cable it is best do do so with the cables perpendicular to each other.
6) Not sure who is doing your drywall but let your contractor know to be very carefull with your cables. I had a great contractor for my basement and HT room but he still managed to destroy one of the speaker wires when he was trimming the drywall around the low voltage box that housed the wire.