I wouldn’t worry about it — that’s merely one of the several gremlins roaming the Alitalia website (incidentally, this is the error message I seem to get whenever I try to manage bookings made through our corporate travel agent, when I’m also unable to select special meals, amongst other things).

That aside, I do agree with one of the posts upthread from @paffendorf — Alitalia has a decent business class product and 2 trendy/newish lounges in Rome (concourse E, don’t bother with the one in pier D) with a chef, a nice [attended] bar and above average food compared to most lounges in Europe. Lastly, it is also worth noting that their short/medium haul product is mediocre at best (not that other European carriers perform much better in that respect but still...), unless you’re lucky enough to get one of the new A321neo with dedicated business class (meaning ‘proper’ seat and the likes), these should soon join the fleet; catering-wise (again, short/medium haul), make sure to select a special meal (I normally go for the seafood option, way better than the standard choice without a doubt) and ask for a shot of limoncello after the meal

G