Cailin, a trick my Mum taught me is that meat tastes better if it's rested before serving (so that it can relax) so I take my roast out and the turn up the temp while I'm making my gravy. The 5-10 minutes on a higher temp seems to crisp up my potatoes nicely.
Also do you put your veges on your hot shelf? Most ovens seem to have one shelf that is a bit hotter than the others (I've found it's the top shelf in conventional ovens and in front of the fan in a fan forced oven).

Then again I usually just use the slow cooker these days - it's easier than twiddling knobs and juggling with shelves.

ETA - totally off-topic but I love your new ticker Sarah!!