Kevin, Get An Archetect. Get an archetect what ever you decide to do. It will cost you about 10% of the construction cost, but will be worth every penny you spend. I see many additions that look like an addition, and hurt the sale of your house. I bought a 2br house with a less than perfect house plan. Wanted to add a 3rd bedroom, and a larger LR window.
I ended up with that and a new entrance and deck, and a floor plan that worked. People now say the house looks great, much better than original, and it has the 3rd BR and Huge deck. The archetect came up with some great ideas, and acted as the control on some of my stupid ideas. Or I would give him an idea of what I wanted, and he made it integral to the overall plan.
Once I had the plans, I could take them to a contractor and get a specific bid. "Follow the plans, match the existing work." No Exceptions! After a year, I can't find a single thing I would have changed. FWIW in Montana, Additional bedroom, new entry, some large picture windows, big deck, new gable roofline, new interior LR, DR sheetrock, lam floors came to $70k, archetect was $6k. House appraised value increased $120k in 6 months over construction. You can't tell any remodling was done at all.
Hope this helps.....
Rich