Depends what you want to see. If I was doing it I'd go clockwise so from Inverness head towards John O Groats (I'll apologise in advance JOG is a complete disappointment...…….) En route to JOG you have Dalmore Distillery at Alness, Glenmorangie just a bit further north at Tain. On the way to Tain you can take a detour to Portmahomack - nice village and cracking beach. After Tain there is Dornoch, lovely beaches and campsite and Dunrobin Castle, some good mountain bike trails. After Dornoch there is Clynleish Distillery at Brora (another good beach). After this you are pretty much enroute to JOG, bit of scenery but not really much else. I spent a year working in Wick and it doesn't have a lot going for it, some nice beaches at Reiss just north of Wick. JOG your next port of call - few minutes will be plenty lol. If you have the time it is worth a trip across to Orkney - either with the vehicle or just on foot (various ferry options). Orkney a stunning place - loads to do and see and could easy occupy a few days of your time (maes how, ring of brodgar, skarra brae, Churchill barriers. Italian Chapel, Highland Park Distillery) some cracking coastal walks, great for diving and sea kayaking etc.
As you carry on west towards Durness you pass Dounreay, some cracking beaches along this road and very scenic. Bettyhill, Tongue and Durness are along this way - same again good beaches etc. From Durness you have the Smoo Caves and Sango Bay, some nice craft outlets at the Balnakeil Craft Village, campsite here too. On the way south it is pretty spectacular - a definite would be a walk down to sandwood bay - just remember if you have a dog it must be on a lead - land is owned by john muir trust and pretty strict about dogs. On the way down its all a mix of small villages and places to walk, go the beaches etc. At Lochinver you can walk inland and walk up suilven - allow all day though its a fair trek in before you start to head up. You also have the bone caves just before Elphin - not too far off the road and nice walk in. A bit nearer Ullapool you have Stac Pollaidh - nice easy walk.
Ullapool probably next - cracking beaches, nice golf course and large campsite, ceilidh place often has live music on at night and the usual bars and craft shops. Can get the ferry to the Western Isles from here.
Gailoch probably next big town, lovely beach, golf course and large campsite. From here head towards Shieldaig and Torridon - some cracking munros to climb around here. Again few campsites around this area.
Applecross via the Bealach na Ba be another definite, campsite here too and a must do would be seafood in the applecross inn. Some good areas here for sea kayaking.
Depending on your time a visit to Plockton and on over to skye be an option too.
Hope that maybe helps you. Like others have said it is a victim of its own success, not sure if there are still as many Ferrari's and the like doing it but they defo didn't like to pull over on the single track and were an absolute pain in the a**. Worth booking ahead for campsites, although you do see lots of folk just wild parking. It is crazy busy in summer, I reckon May a good time. Anything else ask away.