So I am off for a week in a caravan in the Lake District with the family. Forecast is for rain ALL WEEK. Plenty of jigsaws for the kids already packed. Family arguments all but guaranteed. Perfect opportunity to hide myself away and make some tunes! 
Shame your hols weren’t last week! Proper hot!! I don’t have either of the volcas, but I have the rest of the gear you’re taking - those should be lots of fun for sure Hope the different location inspires you to create something cool!
I find the Keys much more interesting than the Bass (which somehow never sounds very melodic to me), and the delay makes it fun.
We have a winner! Although as they’re so little I might see if there is room for a stowaway!
There is a certain overlap between the bass and keys but keys has multiple voicing, polyphony and a much more expansive sequencer/motion control. And you have delay in there too (setting a short delay on the keys and a longer one with the monotron gets really interesting rhythms/patterns going).
i also find the keys more interesting than the bass. but i constantly hear people saying “while the bass is no 303 it has plenty of depth to make its own unique sounds.”
Splitting/tuning each VCO on the bass differently certainly makes it interesting. Plus to can have two or three different sequences going at the same time (although they are all tied to the same filter and envelops). I think bass compliments keys really well but keys is still my favourite of the two.