Hi Vera! I've been to a cosmos tour last year and I must say, it was worth every dollar I've spent! True. It's like whirlwind type of travelling and frankly, you'll only stay a couple of days in each city given the time constraint. However, it's ideal for folks who don't have all the time in the world like myself. I love the fact that I was able to see so much in so little time!
I went on a 13 day tour that covered London, Paris, Lucerne (Switzerland), Rome, Venice, Pisa, Florence, Verona, and Lugano. Advantages of joining the tour: No need to plan since everything is taken care of, all breakfasts and some dinners are inlcuded, some city sightseeing tours (guided) are included like in lucerne, paris, venice, and florence, transportation never a problem, etc.
drawbacks: hotels were 3 star at best, optional tours are pricy but necessary, such as the tours to the sistine chapel and mt. titlis , which I highly recommend, long coach rides but bearable since there are restroom/lunch breaks (autogrills are fun!) every couple of hours, again, not enough time for each city, although don't be discouraged since you'll be given free time to explore on your own, daily rigid routines which require getting up about 5 am (which I did not mind at all), etc.
Bottom line: obviously, joining tours got its pros and cons. But for first timers and maybe for those who don't want the hassle of planning or have only limited vacation time, hands down, tours are the way to go. I'm positive.But then again, I don't have anything against independent travel, which I do sometimes, time permitting. It's your call.
This was the itinerary:
http://www.affordabletours.com/search/tours/17449/Btw, I booked mine from affordable tours online but I believe you can have your trusted travel agent book this for you as well. All in all, I'd say I've spent a little under $10,000 for two but this is net (this covers everything, including an LV bag, murano glass, venetian mask, several other souvenirs, did not skimp on meals, and joined almost all the optional tours). But land package only costs $1700 (September rate), which is dirt cheap. Airfare can be arranged for you as well and I payed like less than $1000 per person roundtrip (open jaw:Chicago to London, Rome to Chicago)
Actually, I will be joining another European tour this coming Jan. 31 this time with Globus, which I'm pysched about! I'll do a trip report when I'm back. Hope this helps.