No experience of Macerata, Urbino or indeed Le Marche myself, but looking at the map / logistics, it's certainly a sensible location, with the small caveat that Bologna to Macerata, plus Macerata to Rome, will effectively be half day transfers (3.5-4.5 hours on trains, plus the faff at either end). Not awful, but I always see if I can find short transfers, which can influence the locations. Hence I see the logic of staying in Urbino, which reduces the transfer time from Bologna, but makes the train transfer to Rome a 5+ hr journey including backtracking to Bologna! Once all the faff is factored in, that's effectively the best part of a day wiped out.
My only other thought will be in finding a location that feels very different to the cities that you'll also be visiting:
- Venice is a unique experience, but with heavy tourism;
- Bologna will mostly give you a break from other tourists, being a functional city that can still appeal to tourists, especially those who have a passion for food
- ?
- Rome: A large capital city, with all the bustle that carries, plus a heavy concentration of tourist interest (and tourists in those locations)
Thus I might be looking for something rural / coastal for that 3rd trip, something to break the pace a little and provide a little tranquillity and/or somewhere to hire a car allowing easy exploration and really getting out into countryside.
Alternatives?
Have you been to Ferrara? It's on the rail route from Venice to Bologna, which would massively improve the transfer times. It's also a proper charmer of a place that's surprisingly under-touristed. The centre is mostly pedestrianised, with cars mostly excluded, so walking and cycling are the ways to get around, and it's flat so both are supremely easy. There is a lovely evening passeggiata, a weekly central street market, castle with moat (and large fish in it), good food, and a lovely gentle cycle ride around the historic walls that are mostly intact still, along leafy cycle paths. If chosen, this easily slips in between Venice and Bologna bringing your train transfers down to 60-80 mins, followed by 2 hrs (plus faff at either end), which buys you another 4-5 hours of proper holiday time.
Montepulciano may not be as good logistically, especially as the train station is nowhere near it (Chiusi-Chianciamo Terme can often be more convenient than Montepulciano Stazione, as there's a decent bus service for the former). It's the classic Tuscan hilltop town, with charm in the centre, plus super wines (to my tastes). There is tourism, but not excessively so. There are some decent day trip options by bus, but hiring a car here would be a good option, albeit if doing this I'd probably look for an agriturismo near to the town, rather than in it (but ideally walkable, or at least in range of a taxi, so you can enjoy an evening or two in the town itself)