OK, I know you already bought a Synapse, but since I had taken the photos of the stuff I'm packing in my SA this weekend, I decided to post it anyway.
This is a combo of my clothes and Mrs B's clothes, which all fit in the 15" Eagle Creek sleeve.
I decided I will leave my MBP at home and just bring my iPad to my meeting. So here's the iPad w/cache and my other random stuff.
Here are the toiletries.
I didn't take a pic of the SA all packed since it still looks empty. There is still a ton of room in there. I think that for the amount of belongings you want to bring, and given that you also have a Ristretto, you'll find the Synapse just fine. A compression sleeve or some packing cubes will go a long way to keeping things organized.
FWIW, I'm also planning to get a Synapse in a few weeks to use for casual summer traveling and to haul my crap around. The SA is actually too big for my day-to-day needs, but I'm thrilled to have it for when I need a backpack-plus.