I cannot begin to count the number of hours I've spent researching/ordering windows.
First and foremost, if you do not want to spend a lot of hours on windows, make sure your architect specifies every single detail re every single window in your plan......brand; specific line in the brand; style (single hung, double hung, casement, awning); fixed or operating glass; grid size and pattern; jamb depth; colors; whether glass must be tempered; whether window must meet egress; brickmould or add your own trim (and what does the trim look like?).
We went the bare bones route with our architect. Most of the finish details were left to us to specify. The disadvantages. as noted above, largely involved time. The advantages included keeping costs in check by knowing exactly how much window we needed (fiberglass is overkill in our climate) and avoiding certain expensive types of windows such as French casements.
I ended up placing orders with 3 different window manufacturers, kinda unorthodox. But by doing so, I was able to reduce my window costs 35% from my initial price quote. I was even able to use a new Marvin product, a venting picture window. The whole window pops out and has a screen around all four sides. I put two of them in the front of the house. These turned out to be cheaper than the Jeld-wen French casements I initally spec'd.