There is a very beautiful five-star hotel, located in the former royal residence (booking.com) and perhaps one day we will stay there.
Though now, with a small child, we stay only in apartments with several rooms, so we found a fairly inexpensive option 5 minutes from Alghero (40.566538, 8.351516, booking.com). The nearest good supermarket is here 40.570878, 8.337686.
Alghero has a full-fledged old town, a rarity in northern Sardinia. However, unlike other towns, it is much more interesting to walk around the old town, along the walls. We parked here 40.562166, 8.316619, but out of season you can search around the old town.
The first walls appeared as early as the end of the 11th century, due to the strategic location of the port city.
At the time of our visit, the city was hosting a Rally World Cup, a rather significant event in the world of motorsports.
The inner streets are quite narrow and not very interesting, though we walked there as well. Sardinia was heavily involved in World War II and Alghero was bombed. If you are interested in this time period, I recommend the mini-series Catch-22.
For dinner we went to different places. On the outskirts of Alghero we found Quintilio Restaurant (40.544331, 8.321079). In movies, such restaurants are usually shown in the end, when the main characters meet.
If you have a car, we also recommend a dinner at Bosa Marina (40.290097, 8.477541), reachable by a beautiful road near the sea. The town has a number of restaurants along a very wide beach.
And we also visited the country restaurant Ristorante da Bruno (40.603619, 8.280066).
In terms of beaches, the northwest loses a lot to the northeast. So if you want to go to the beaches, you should stay around Olbia. We did not go to the city beach of Alghero, but near the town found Maria Pia beach, surrounded by a pine forest. Parking is here 40.585675, 8.308845, then walk a little bit through the forest. You can also get here by AF and ALFA buses (schedule), to bus stops Alghero Viale I Maggio Fr.la Palafitta or Alghero Viale I Maggio Fr.scuola D'arte.
Getting there: Alghero has an airport where many low-cost airlines fly. You can also fly to Olbia and then drive to Alghero in 1.5 hours. There is a new highway under construction, so the road is pretty convenient. There is also a train station, but the speed of trains on the island is not high enough.