Those are all great places. If you are trying to keep it affordable for guests, then Ireland is probably out given the Euro and cost of everything over there. We chose Mexico for that reason - a lot of our family is coming in from Chicago and it was still reasonable, plus they can stay at an all inclusive resort. The Southwest is also beautiful, but depending on where you get married it can get pricey. I would think about what's most important to you - a specific setting, time, month, number of guests. Sedona is beautiful!