Originally posted by onlineflyer A word of caution. Italy is known for its pickpockets and petty thieves, especially in Rome. Guard your gear, whatever you take.
And V-A-V that warning, some locations are notorious for thievery, notably the Spanish Steps.
And I also agree with the recommendation that upgrading to a K5 II will significantly improve your images, especially hand-held, high ISO interiors. And I also doubt that the 70~300mm will be used enough to justify taking it along. Were I to assemble a going-to-Rome set of lenses from scratch, I would select either a Pentax 18~135mm or 16~85mm plus a Sigma 8~16mm.
Below: interiors of St. Peter's taken with the 8-16mm