I'm not an expert on Plextools, but I have used them for a while. In part, your success with them will depend on your media and the write speeds available with other software you use in conjunction with Plextools.
I assume you want to know about the Drive Settings that would be best. Generally, these should be checked as default, but make sure (if they aren't) to check PoweRec (P/R) and Autostrategy (A/S). The A/S function is the 'intelligent' write strategy part, which will help control the write on your media (depending on its media ID). If, for example, your media of choice is Ritekg05 (pretty good in my experience), make sure P/R is also checked (it will be by default). The Plextor burner (my model is px-716a) will burn it at no faster than 8x--which by my burn tests show is best for it (and the Plextor burner is programmed to burn it at).
An exception to this would be Taiyo Yuden TY000-T02 media ID (either Sony DVD+R 50 pk 8x media from Circuit City or FujiFilm DVD+R 50 pk 8x from Best Buy [both say "Made in Japan"]), which the Plextor will try to burn at 16x. This is one write strategy that should not be followed. Therefore, uncheck P/R, and if you have a separate burning software (I have VSO's CopytoDVD), you can set its write speed (under Writing Devices>max speed for DVD media) to 8x, and your Plextor will burn those at 8x--and give you a great burn with low error rates on PIE and PIF tests. This would be the best concrete example I could give you of something specific, as well as a specific exception where you would not want P/R checked.