First of all:
How advanced would any such life have to be to motivate a crewed expedition to the outer planets?
Any life form of any type would motivate a crewed expedition - from the simplest, most basic cellular life on up. If we found any life on any celestial body, we would be thrilled.
As for Europa, it has a fair amount of water, and an atmosphere of oxygen. There are theories that it has water underneath it's ice-sheets that could support life as we know it. If this theory is correct, then most marine life as we know it today could theoretically live on Eurpoa.
Titan, however, has a mostly nitrogen and methane atmosphere, so most life forms as we know them on earth would not be able to survive on Titan. That said, we have found life forms that don't need oxygen. In fact, some scientists from Cornell believe methane-based life could exist on Titan. It's unclear what exactly that type of life form would look like, as we would have to define how an oxygen-free cell would perform, but it does appear to be possible, at least in theory.
Until science gives us more answers as how such cells can/do/might behave, you'll have to use your imagination and some hand-waiving to get life on Titan. Europa could/would be more like life on earth's seas. Regardless, any life at all of any kind would motivate a crewed expedition for sure.