I hate to be the bearer of bad news, but laying out your city is not a one time thing. It is a constantly fluid, game-long balancing act. Rearranging your entire city is something you will probably do more than once as you go along. The building sizes change drastically as you advance through the ages. Special/event buildings will influence your choices. GBs are always a challenge due to their size and varying proportions. If you use regular coin/supply/goods/cultural/military buildings after Industrial Age, you'll have to work 2 lane roads (that can only intersect on even numbered intervals) into your layout calculations. There is no cookie cutter, one size fits all formula. It's something we all work on all the time. It's part of the challenge of the game, and for many of us it is one of the most enjoyable parts.