An easy one is to pop over to Dores, just a few minutes out of Inverness. It sits on the northern bank of Loch Ness and has a cracking view down the length of it from a nice wee shingle beach were I spent many a night in my youth. Plus, the Dores Inn pub serves brilliant food!
If you're in the city centre and need to kill an hour, go for a walk through 'The Islands' on the river and along the bank, helped keep me sane when I worked an office job!
Oh, if you're driving up the A9, I always stop at the Ballingluig Motor Grill or whatever its called - it's a greasy spoon, proper food at a proper price, better than Bankfoot/Aviemore in my opinion.
I've not lived there for 10 years, I'm actually struggling to think of proper suggestions!