While I love the look/idea of the classic khaki/beige trench coat, I don't think that colour looks all that great on me, so when I do decide to wear someting beige-ish, it's stone/mushroom coloured pants or a taupe-ish handbag.
That said though, as someone earlier in the thread mentioned - it depends on the shade. Believe it or not, there *are* certain shades of camel that look nice on me, but in general, beige-y tones are not all that great.
I've got blonde hair, fair skin, blue eyes. If it's just plain beige, and close to my face - it kind of washes me out.
I do have a casual beige-ish summer skirt, I've got stone/mushroom-y dress pants, and a stone, or "greige" summer handbag. I would love to have a classic beige/khaki coloured trench coat, but the thing is - it would take some serious looking to find just the right colour, so I haven't bothered. If I found a coat that I loved, and it was just the right shade, I'd certainly buy it, but because "beige" is a difficult colour on me to begin with, I don't really go looking.
One last thought - I just realized that the only time I wear any shade of beige/khaki/stone/mushroom or similar colour is during the late spring and throughout summer. It's a way to lighten up my wardrobe without going full on into white.
I really think it depends on your colouring - if the typical beige/khaki type trench coat didn't wash me out so much, then I'd definitely be buying one. This is one of those 'classic' and timeless items that I'd love to have - it's just that the colour is hard for me to work with, so beige/khaki/and all other similar shades are usually worn away from my face, and further - these types of colours are usually only worn during late spring and throughout the summer.
Not sure if this helps you at all in terms of deciding which classic and fabulous trench to go for, but thought I'd throw my two cents in anyway.