You really should think about Pentax as there's one major reason to pick it over OM or Nikon if you're planning to have both digital and film bodies:
All Pentax lenses will fit all of their DSLRs, they'll all meter and shoot too.
I would strongly suggest buying a good condition Pentax MX and Pentax-M 50mm f1.7 to see how you get on, at the moment you should be able to sell it for at least what you paid so it'll only cost you a roll of film or two if you decide you don't like it. The MX is a purely manual mechanical body where the batteries only power the light meter, but it's small, relatively light, has interchangeable focusing screens and two winder options, and until the LX was released it was regarded as their professional body. That 50 is capable of embarrassing lenses a quarter of its age too.
If you do get on with it but want more features then look for an LX (either one which has been overhauled by a reputable business or budget for a CLA, they're great cameras but need to be maintained properly). Compared to other pro-spec SLRs it's tiny but a solid, reliable camera with all the usual bolt-on accessories available.
As for lenses... I have most of the more common Pentax ones, here's my pick from what I have:
SMC Pentax 28mm f3.5 - I use it for landscapes so the speed really doesn't matter, the lack of distortion and the razor sharpness more than make up for it. There is a smaller and more common Pentax-M version which is almost as good.
50mm/55mm - my three favourites are probably the SMC P 50mm f1.4, the SMC P 55mm f1.8 and the Pentax-M 50mm f1.7 listed above. They all have slightly different strengths so it doesn't feel like duplication to have all of them. There was a 55mm f2 as well which was identical to the f1.8 but with a baffle to stop the aperture opening up as much - general opinion is that this was a marketing stunt and the lenses are more or less even in performance.
Telephoto - my two favoured lenses are the SMC P 120mm f2.8 and 100mm f4 Macro, neither is particularly easy to find. There are Pentax-M versions of both, the Macro is fairly common but the 120mm less so as most normal users bought the 135mm f3.5 instead (which is also a brilliant little lens).