No matter the distance, please don't drive into Paris (unless you want to cause yourself a nervous breakdown)!
If you intend to visit Glasgow and Edinburgh too, I'd avoid driving into these cities if you're not familiar with them and haven't driven here. Edinburgh in particular is difficult to drive and park in, with lots of one ways and enforcement cameras. More generally, if you're talking about hiring a car and driving into the Highlands the you need to be prepared for narrow, twisty roads with sheep and lot of other tourists on them. If you're a confident careful driver you'll be fine, but be aware of it. The road trip mentioned earlier is a bit long imo for a day - 177miles in one day will have you just driving all day I think.
As mentioned there is a lot to see in both Edinburgh and Glasgow to easily fill more than one day each. The HOHO bus may be a good way to see things and travel around in Glasgow cause many things there are quite spread out and not in the city centre (you could take the subway or train instead). There is a HOHO bus in Edinburgh too but the city is smaller and more concentrated so you may be as well just walking. Having said that, if you're more interested in countryside there's nothing wrong with bypassing both cities and taking a countryside visit.
Bear in mind the cruise won't actually dock at Glasgow - it will dock at Greenock, a port town about 25miles from Glasgow. You can take the train from Greenock to Glasgow - there are very regular trains which take about 45mins and cost about £8 rtn (it's a high frequency commuter train, so you don't need to book). Driving from Greenock you've got all around Argyll and Loch Lomond. You can take th ferry across to Kilcreggan (or to Dunoon) or just drive across the Erskine bridge and head into the loch Lomond and Trossachs national park or to somewhere like Inveraray. You could maybe head up a far as Glencoe, although it's a lot of driving (and maybe not worth it if it's rain and low cloud)
Similarly at Edinburgh the ship may dock in Leith, which is a port area of the city and you'll need to get a bus or cab to the city centre. I would think twice about picking up a car in Leith cause likely you'll have drive through the whole city to get where you're going.
Alternatively it'll dock in rosyth which is on the other side of the Forth about 15miles away, so again you'll need transport to Edinburgh. If you're docking in rosyth and want something other than a city visit then you could drive up to St Andrews and the East Neuk. It's an easy 1hr drive on freeway and main roads and a nice area with nice coastline.
Although the cruise trips may not suit, I believe there are a number of independent tour companies who pick up from the cruise terminal and provide tours. I know Discover Scotland Tours pick up at Greenock. I think others may also pick up there and also at invergordon - just Google them and you should find them. These may offer a good option to see as much as possible in a day without the stress of driving on the left on unfamiliar roads in an unfamiliar car (btw the vast majority of cars in Scotland are manual or "stick" shift, not automatic).