Our stories and goals of riding are very similar. I purchased a Specialized Sirrus Sport from my LBS on April 7th of this year for the exact same reasons that you listed. I think I paid a shade over $500.00 for it. I'm 5'11", 250# and turning 50 next month. The Sirrus Sport is a good bike for doing what you are wanting to do. However,,,,,after riding it for about 175 miles, I made the mistake of test riding the Specialized Roubaix SL4 Sora. What a huge difference! I bought the Roubaix on June 20th and have put 383 miles on it so far. The Roubaix is a 100% carbon fiber frame is much lighter than the Sirrus and the gear set gives me a much smoother, easier spin. The multiple hand positions is also a very big plus. It has made cycling much more enjoyable for me. I wish I would have saved my initial $500 investment and went with the road bike first. As of this morning, I am now at 240.7# and am looking forward to shedding many more pounds. My wife has noticed the difference in me, so last week she became the proud new owner of a Specialized Dolce Compact and we are having a blast riding together.

Good luck on your search and if I could offer one bit of advice, test ride as many as you can before you make your mind up. And when you do, make sure that the LBS gives you a proper fitting. Have fun!