I went to Monte Cassino a few years ago.
Biggest problem was finding somewhere to stay on the way down - everywhere was full due to Italian holidays
ended up riding all the way there - arrived about 10pm
Good campsite in the town - I decided to say there and just do rides out, Pompeii, Anzio, Taranto etc
If you're after military history best take some books and do it yourself.
The Italians dont seem very interested.
there is a small museum in the abbey but its mainly about the destruction and rebuilding.
Plenty of shrapnel to be found anywhere you stop on the way up.
The museum in Anzio was closed the day I went - I think its in the council office - best to check.
I've just done a big euro tour with a small group and I say go on your own.
groups are a pain in the arse to ride with - evenings can be quiet but then you are more likely to meet other people
enjoy anyway