The different flavours of tour all have their merits. The big groups you meet a lot of people, all motorcyclists, so fun and interesting. Usually the the big groups naturally break down into those that want to race ahead with the guide, those that cruise along sight seeing and then serious photographers. IMT do an excellent job of accommodating the various sub-groups. The self guided tours do give you a bit more freedom but sometimes can be a bit lonely, especially in a country where very little English is spoken. Example: Portugal lots of English spoken, Spain not so much. I've toured unguided, self guided and group tours. My favourite is smaller guided tours with not much sightseeing but then I've been riding in Europe for many years. IMT are very good helping customers decide what style of tour is right for them. One caution I'll add is that if the tour is labelled "expert", in good weather almost anyone with few years experience can ride it, but if the weather turns bad (Alps, Pyrenees, any mountain riding) it can be seriously challenging! Regarding "dress code" ....very casual, other than the obvious.. like bare feet, whatever you feel good in. Dinner in Europe is always later and usually "served" as opposed to buffet style. My approach is to either nap or go for a good 2 hour walk before dinner, it's rare that they start serving before 8 pm.

You would have to ask IMT directly. They mainly runs tours and also rent bikes but I would guess that they could help you.