Here are a few steps, for when I do a project....

1. Number one rule, ALWAYS and I repeat ALWAYS use references. At least a front and sid reference will help you plan out where all the vertices should lie at.

2. Start the base mesh poly-count as low as possible. In your case I would use a polygonal cylinder and set the radius subdivision to something like divisable by 4's, such as 8, 12, 16 etc. but I would not go over 16.

3. Once the base is done, you can then start by slowly adding more divsions for where the windows will lye, but still keeping in mind you still want to keep the polys as low as possible.

Also, you mentioned about tried booleening circles onto the suacer, and you where almost correct. You can still do booleens, but what you did not do before hand was doing step 3 as well as step 4. I have posted an image below which I will explain after step 4.

4. When working with booleens, you will never get all perfect quads. The trick is making sure that the first 3 steps are completed, and then merge the vertices that are creating nGons.

Down below, is a gif animation on an example of step 4....