I have a wooden floor in the toilet and I want to put down a
hard-wearing tile which is easily cleaned and is hygenic. Of all the
different kinds of floor tiles available, which is the least absorbant
and most resistant to staining etc. from urine? Which do you
recommend?

Much depends on what is underneath the wooden floor.

If you have solid concrete then large ceramic tiles would be my choice.
(minimal grouting)

If you have slightly bouncy wood then top grade cork tiles with a
sealant would work. A bit retro - but so what.

A really effective solution to (what I suspect is your problem) would
be to mount the bog in a large ceramic shower tray.
- you might just start a fashion

Even better - an optional 'squat bog' - like the ones they used to
have in France - and still have in the Far East.

(Note: I have not suggested a male urinal - because men are of different heights)

Despite what many people think, bare wood is very hygenic since the
tannins in the wood kill microbes, but it obviously not the esthetic
solution.
I would recommend PVC sheet-flooring.  One seamless piece could cover
the whole floor, and the sheeting is flexible enough that you probably
would not have to worry about slight unevenesses in the existing
wooden floor or whether it gives slightly.  The design can range from
parquet (wood-like) to many tile patterns, to designs only available
in PVC.
This page of a website indicates that the surface can be of different
quality, but I expect that any manufacturer offers a similar range of
products:
http://www.gerflor.com/en/contract/zbenefit.asp

Some people choose a color and design that conceals the problem, which
is practical for a guest WC.

Just how bad a shot is your husband/partnet?

LOL

Winkypop:  It's the little boys ... 
But as the sign in one filling station put it:  
  "We aim to please.  You aim too, please."