I have found that lowering your transcoding bitrate to 7MBps MAX resolves most of these issues. Burned DVDs are NOT as reflective as stamped ones. Even though the DVD spec allows up to 8MBps max for video, some stand alone players simple can't read that much data from burned (less reflective) discs. Its like trying to swallow a big bite of food. Maybe it'll go down, maybe it'll get stuck. Best bet is to take smaller bites. Thats exactly what is happening, the players are "choking" on the data. The difference in bitrate is not really noticeable to most consumers.
I ALWAYS burn at 4X. Give your laser time to burn the data properly. Think of it like a suntan. The longer your exposed, the deeper the burn.
Taiyo Yuden is said to be amoung the best brand of DVD media. I use them and have never had a problem (or a defect for that matter).
http://www.cdrdvdrmedia.com Verbatim is also supposed to be good. (I haven't tried these yet)!
Sticky labels can cause the disc to spin unbalanced. Plus, when the disc warms up from playback, the label can peel up.
Stick with the -R format. +R is not as compatible (but some may argue that it is), unless your making dual layer DVDs. My personal experience with the dual layer -R format did no go well. I bought a 25pk and I think maybe 3 worked. My understanding is +R is better for dual layer (but I avoid dual layer completely).