I like both - I haven't been to the Bourbon in Disney, but we have one about 10 miles from my house and have eaten there several times. Excellent meats, good sides, good sauces, all around a nice high-end steakhouse experience.
Same goes for Yachtsman - have had some excellent meals there including a few 'splurges' with family and friends where we went nuts with appetizers, sides, sauces, and wines and ran up some hefty bills there too. Neither is cheap, but both use very good cuts of meat and high quality.
On dress code, the Disney Bourbon will be as loose as most other Signature restaurants - they don't forbid shorts - they essentially want an attempt at not looking completely slovenly - shorts are fine, but not bathing suits, gym shorts, etc. sweaty stretched or ripped T-shirts may be looked badly on, and graphic t-Shirts with profane messages might be turned away. ANyone with golf, dress, khaki, or bermuda shorts and a crisp polo or button down shirt would fit right in just fine. Same goes for Yachtsman.