Alex, these cameras are a lot of fun, indeed. You will enjoy using them. But you should be aware that other than the Mamiya TLRs, which have interchangeable lenses, and the very rare and expensive Rolleiwide, these cameras' lenses are the 35mm equivalent of 50mm or thereabouts.
Of course the Rolleiflexes are great cameras to get -- but I sense from your note that your wife won't be happy with you spending a lot of money. So I won't even suggest those. Instead, here are a few worth considering, all of which have excellent lenses, 4-element Tessar-type designs, and which should be pretty reasonably priced:
Yashicamat 12, 124, or 124G -- the latter two have a meter, but that isn't critical; most folks use handheld meters. These have the film/shutter cocking crank, which is very quick to use (Rollei pioneered this). Focusing knob on the opposite side.
Minolta Autocord -- wind/cocking crank; focusing lever below the lens.
Ricoh Diacord -- focusing levers on either side of the lens (very convenient). Knob film wind and separate shutter cocking lever.
Yashica D -- later models with Yashinon lens (NOT the Yashikor). Focusing knob and film wind knob; separate shutter cocking lever.
Rolleicord V, Va, Vb -- similar features to the Yashica D. Rolleicords have a lever below the lens that you push one way to cock the shutter, then pull back the other way to trip the shutter. A little odd but you get the hang of it.
A bright image on the focusing screen is a real benefit when using a TLR. Having a fresnel screen makes a difference; also, having a wider aperture viewing lens makes a big difference too. The best of this list in this regard are the Yashicamats and D, and the Autocord.
In terms of build quality, the Rolleicords and the Autocord are best, but the others are good too. Yashicas have been known to have problems with frame overlap -- the film transport gearing isn't the best. But many people use them with no problems.
In terms of an overall combination of build and picture quality and ease of use, I'd recommend the Autocord, but you can't go wrong with any of them.