Travel with a photography/camera backpack [closed]

I am m/29 and am about to leave for two weeks backpacking trip to Europe (abt 4-5 cities).

I have a camera backpack (lowepro fastpack 250 aw ii - http://store.lowepro.com/fastpack-bp-250-aw-ii). Now considering this backpack that I already have, I want to know which second back I should be choosing for my cloths. When it comes to cloths, I can pack light but will be still caring stuff which can fit inside a 25-30l bag..

Below are three options I have for second bag:

(1) Rolling/Spinner suitcase: I have a Samsonite Spinner 21 rolling suitcase. Its usually bigger that what I want for my cloths. I can also accommodate my camera backpack inside this suitcase in addition to my cloths. But still this is a rolling suitcase and I have heard that traveling in European cities/trains with rolling suitcase might not be good idea.. I can also take this rolling back as carry-on and avoid checking in.

(2) 55l/65l backpack: I can get a bigger backpack, and accommodate my existing camera backpack inside this bigger backpack in addition to cloths. I have never seen or heard anyone packing like this - especially considering size of my camera backpack. But with this option, I might need to check-in my bigger backpack as this will be bigger than carry-on size.

(3) Duffel bag: I can get a medium size Duffel bag just for my cloths. This can be bit light weight. But I do have to always carry this which might be inconvenient and my one hand will be occupied always..

Can anyone please share experience and suggest me what will be best choice that I can make here..

Thanks !!