Okay, this is getting a bit comical. Have to agree with the other gents comment that this must be the same "tourist crap." Tourist crap or not, it's a nice scene and painting. I reside in Seattle but bought while on a biz trip to SFO - from a place named Ravanelli's on Grant Street. After buying and having shipped home, came to learn that the store owner has little to no integrity. But perhaps that’s a story for another time. And we're happy and pleased with the painting and framing. I was not looking for anything "valuable" rather just something nice that went with the home decor. So we got what we wanted. But my curious search for who "Lucas" is led me here. As the other guy said, just enjoy it for what it is. I would post a photo of it here if I could. All the other descriptions are spot on: Old villa on right, cobble stone walkway down incline with colorful flowers near front left corner overlooking what appears to be a Mediterranean coastline, also on the left, and the ocean in the center (more or less) with clouds above. Quite nice actually. Ours is about 57" x 46" (incl. framing).
So can't answer the question as to who Lucas is but know it sounds like a mass produced piece. Enjoy it nonetheless and stop searching for who Lucas. Probably a fictional character anyway - yes, that's my cynical side popping up.