I have the E-M1, 12-40 f2.8, and the Olympus primes (12, 17, 25, 45, 60, 75), plus a lot more. I don't have the Olympus 40-150 f4-5.6, but I have the Panasonic versions (45-150, 45-175, 45-200), and the Olympus 40-150 f2.8.
For me, when I travel, if I'm bringing lenses that split at the 35-45mm region, I am constantly wanting the other lens, and thus bring two cameras so I don't have to change lenses. I find it more convenient to use the Panasonic 14-140mm mk II and add a couple of primes for low light or narrow DOF applications. With the 14-140 I also like to take the 12, 17 and 45. You can look at the Olympus version; I also shoot Panasonic so I have that version.
I like the primes for interiors (museums, homes) where the lighting is dim; the speed of the lens helps with focus even if I'm stopping down for DOF.
The 12 is expensive; you can substitute the Olympus 9-18 if you want ultra wide angle. That's also a very light/small lens.
12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40, 12-40
Did I mention the 12-40?
Fast primes are great, but the 12-40 is an excellent walk around lens.
My other suggestion would be the 75mm. Those are my two lenses that I carry with me everywhere. I hear great things about the 40-150 kit lens, but personally I'd rather shoot the 75 and crop in a bit. The lens is so sharp, it handles cropping while still retaining its sharpmenss.