I would certainly recomend getting a lens that minimises the need for a WA adaptor, for the reasons already mentioned. Even more so on a camera without EVF, because the adaptor forces you to use the LCD, which is famously a pain in bright conditions.
It seems that the 35mm SLR world has overwhelmingly voted "28mm" as the "natural" wide limit for astandard zoom lens, with 24mm as runner up, so aiming for the equivalent of at least 28mm in a good digicam seems wise.
The only counterpoint I have to add is that in my experience, telephoto adaptors are even messier to work with; they tend only to be usable at or near the maximum focal length, leaving a gap between the focal lengths possible with and without the adaptor; WA adaptors handle zoom more nicely.
So just do not go wide to the point of giving up long focal lengths that you also like to use.