Visit the medieval part of Turku at Aboa Vetus museum. The city had a big fire in 1827, but its medieval stone cellars and paths can still be seen, cause these were buried under the ground when a garden was built. The oldest parts dating back to end of 14th century.
The information is easy to read (Finnish, English, Swedish). Kids have a play area after each stand. There is a modern cafe place in the museum house. I did not have time to go to the art museum, though.
Although not in Rauma, Naantali spa is one of the best known spas in Finland. It is luxurious and one of the closest to Rauma.
Hopefully Rauma gets its own spa one day, just like it had one over 100 years ago.
I met families with 3 different holiday budgets. A family of 4 had paid a website price of about 200e for the Moomi room in the spa building. The timeshare owner that paid 150e for 5 nights for 2 and extra for the breakfast and spa. And another lucky one with his employer’s discount price of 250e for 2 nights for the 2 room flat in the nearby residence. An additional -50% for the extras such as 10e per spa visit and breakfast for adults makes it close to 200e per night, I guess.
The hotel had a restaurant on the down floor. Two play areas for kids staying at the hotel, although restaurant visitors were trying to get in too. Several pools and hot tubs at the spa, also outside. And it did not feel cold! Holiday Club often invites people to the hotel with a 50e per night deal, but it includes a marketing event for such timeshare investments in hotels (as mentioned before).