I often follow what my mum used to do - cook carrots with potatoes, then mash them. Looks nice, tastes nice. I do the same with potatoes and chopped onions. Again, tastes nice, though the mash tends to be more moist using onions.
Jaimsieboy, I regularly do just that if I'm feeling particularly lazy and don't want a load of pans to wash up. I also put peas, green beans, broc, cauli and any other veg (not put cabbage in) we're having with the meal, in the same pan. Just throw them in at the required time.
Unless you happen to be a gourmet with a particularly sensitive palate you would never know they had all been cooked in the same pan.