The company I work for is going to be moving offices soon, and the new space is completely lacking in power or ethernet cabling right now. About 1/2 of the total office space is a 30'x30' open room, where the engineering team (about 10 people) will sit. Our prior layout was pods of 4 desks facing each other; we'll probably do something similar in this setup (I don't have the exact measurements yet to know how it'll all fit.)
Specifying power and drops for the remaining office space is easy - pick a spot on the wall. But I'm not sure what the best strategy is for a big open room. Slightly raised cable raceways with power and ethernet? Recessed floor jacks? Power poles running down from the ceiling? Also, does it make sense to home-run all the networking to a central wiring closet, or to simply run 1-2 connections for the entire room and use a good switch for all the systems in that room?
Raised floor would be a good solution, it would solve your problem with electricity and networking. It's also easier to change the layout if needed (just move tiles around as needed). If that's not possible, power poles from the ceiling may be a good second answer, but I don't like the visuals.
I would also use a exclusive switch for that room, it'll break the broadcasts, make it easier to expand if more people come to the room and being the engineering team I suppose they are heavy users that will put a single switch to good use.
I would try to avoid putting switches in common areas as people can mess around with the kit, stumble on power cables to it and a whole world of other potential issue. If you can get a raise floor just deploy standard floor boxes with power and cat6 and pipe it back to the wiring closet, if not you could run cabling in ceiling and dropping cables down to the desks, what's the office layout? Single desks or groups of desks in "pods"? With pods dropping cables from the ceiling is quite tidy, with single desks it can look a bit messy.
I recommend you home-run the cabling to one server room if possible, as it makes administering your network a lot simpler. You should try to minimize the number of network switches you are dealing with if possible. Obviously you also need to be careful about not over-saturating the switches with traffic, but worst case if that does happen you can put multiple switches in one server room. That's still a lot easier than dealing with switches separated in different rooms. Also I assume you want some sort of battery backup for your switches, again dealing with UPSes and such is much simpler if all your network infrastructure is consolidated.
As for the network and power drops in the open seating area, I would recommend dropping everything from the ceiling with power poles. Vendors make an amazing array of poles to fit all sorts of different environments so you can probably get ones that blend in pretty easily. Commercial electricians are well-versed in working with power poles and they can be installed very quickly. Also consider that the space you are moving in to probably already has a drop ceiling so you can just run cable trays above that as needed.
Dealing with raised floors is a complete pain in the ass and should be avoided if at all possible. Modern datacenters tend not to use raised floors for lots of reasons, the biggest one being cost. Consider also that normal workers in an office environment will routinely spill liquids on the floor. Do you really want to deal with that in a raised floor setup?
My biggest piece of advice is just keep everything simple. Don't over think this with complicated plans - consolidate your equipment and then make adjustments as needed.