Theres loads of interiors to choose from, on early mk3s there were about 7 or 8
Grey and green fox interior (you dont want that)
Grey CL interior
Blue CL interior
Black CL interior (rare)
Some other CL interior (a sports one apparently) That Ive never seen, possibly similar to grey GT interior
Grey GT interior
Black GT interior
G40 interior (black)
All taken from my "new polo" brochure dated Nov 1990
The ones to go for are the bottom two (look the nicest). The grey GT one would suit a lighter coloured car more imo but Its down to personal choice.
I dont know alot anout later coloured interiors but I would guess that there is the same range of interiors with slightly different patterns on them when compared to the early ones. Altho there are one or two additions to this list that I know of, one says "volkswagen" all over the seats
Another good one is a polo genesis interior but using scirocco GTII front seats which have the same pattern. Theyre the same as G40 seats but are a bit wider and the seating position is slightly different (lower I thinK) A very good mod that.