Heading to Rome for 2 days in October with extended family. Most haven't been before, so looking for a decent-size hotel that (a) could accommodate 7 couples, (b) in a central location to walk to all the major sites, and (c) isn't a crazy expensive chain. Go!
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We stayed at Hotel Lancelot and loved it! Comfortable, charming and great staff. Only 5 blocks from the coliseum and walking distance to the subway. Breakfast included (HUGE SPREAD! )
Look into renting an apartment. It's super reasonable and then everyone can stay together. We were there 5 years ago and stayed in an apt right off Campo dè Fiori and it was awesome. If you want me to check the company we used let me know.