Having switched from a gasser to a diesel last year, you are correct about noise. I only use my RV for about 6 weeks a year vacationing, and every weekend I can. After 5 years with the 32' gasser, i knew what things were most important for my upgrade to a diesel. As the only driver, a diesel was a must just for the noise. Apposing slides with couch and loveseat was a must. A 40' with bunks fit all my major needs for traveling with 3 kids and two 100lb dogs. This will also only be a 5-7 year purchase as I know needs will change when kids are in college. I am already putting together my wish list for what the best layout will be for us for traveling without the kids. For me it will most likely be a large rear bath with dual sinks and large shower. I purchased a 2014 40' Berkshire for $150,000. I have learned from this site and other RV sites that you dont have to be intimidated trying to do repairs on your own. There are enough Fulltimers out there that are more than happy to help you research problems and offer step by step solutions when repairing things. The 5 years with my gasser was very little cost for unexpected repairs. Normal oil changes was about it. Most expenses where by choice for upgrades, but not necessary. Max air fans and vent covers, better TV.
The bigger expenses to be aware of are the tow package and brake system for you toad if you plan on having one. Also, do you need to replace your current car to get one that can be towed? Storage costs are another issue to take into consideration if only using for 5 months. The longer the DP the more you pay for storage.
I have probably spent $1500 dollars in "stuff" for the new DP in the first year. New outdoor rugs, indoor rugs, new bed covers, max air fans, surge protector, ect. It all adds up the first year of ownership as you figure what you want and need to make it your home.