DVD players are limited to 720 x 480 (NTSC) or 720 x 576 (PAL). Upscaling allows them to take video in these resolutions and output in larger, HD resolutions, but they cannot read the HD resolutions natively. This holds true for all dvd players that I know of. Blu ray players are not limited in this way, which is why your PS3 player can handle the AVCHD video.
Many blu ray players are capable of playing AVCHD, though not all. Blu ray standards have been something of a moving target, and AVCHD came a bit late to the party.
Most PAL dvd players will playback NTSC dvd-video without problems. So you should be able to convert the 30fps AVCHD to NTSC dvd-video and play on your dvd players without issues. You might try a free converter called AVStoDVD for this conversion. http://www.videohelp.com/tools/AVStoDVD This converter can also output in PAL specifications if you want to try that.
If you want to convert to divx instead, the frame rate shouldn’t be an issue, but you will want to use an avi container. Do you know the audio codec used in the original video? Divx or xvid video often times uses mp3 audio, and I don’t know if your players can handle that. They should, but this is something you’d have to try. LPCM audio would be safe, but takes a lot more room.