I think ovals would be very interesting to see, although I’m not sure I’d pay attention for a whole race distance.
What I would really really love to see is a feature event that had a series of short races that depended upon some different skill sets of the drivers. For example, you know in the Race of Champions they start at different ends of the circuit? I’d love to see two F1 racers go head to head on a similar theme, on a circuit something along the lines of the part-road part-oval circuit that PM mentions above. If they started at different ends of the course then noone could complain about dirty air slowing them down etc. If the course played to different driving characteristics, then we might see them pushing each other to the limit. Perhaps they could do some quick qualifying to decide the pairs.
Similarly, I’d like to see them in a challenge that was specifically about overtaking. Eg in ‘Need For Speed: Shift’ there’s an online challenge where you do the same short course three times. Once starting together, once starting a little behind the other car, then once starting a little ahead. So, to win, you’re probably going to have to overtake at some point. But I’m sure something quicker or more entertaining could be made up.
But it’ll never happen :(