How to get a sweeter, more full-bodied beer

After reviewing the judges' feedback from my homebrewing competition entries earlier this year, and combining it with my own observations, it's clear that for some styles I am not quite hitting my target for mouthfeel and (where appropriate) sweetness.

I did some research into how you can improve these qualities in your homebrew, and have uncovered the following variables which can be altered during brewing to give a beer more body and/or sweetness:

• Add unfermentable sugars:  This can be done with sugars like lactose, which yeast won't ferment.  This will add a sweetness to a beer like a milk stout.  I've done this in the Stout Chocula beer I brewed earlier this year to good effect.  However, I don't see lactose working well in a Belgian beer. 
  
• Add Calcium Chloride:  This can reportedly enhance the maltiness of a beer.  This is something I haven't tried, but will tinker with in the future.
  
• Increase Caramel Malt:  Increasing the amount of caramel (a.k.a. Crystal) malt in a beer can increase residual sweetness, though if you go beyond 1-2 pounds in a 5-gallon batch you can oversweeten the beer.  I've done a little of this, but could probably do more.
  
• Change the yeast strain:  Switching to a comparable but less-attenuative yeast strain can result in more residual sugar in the beer, leading to additional sweetness and body.  This is something I have considered but haven't tried yet.
  
• Boil longer:  A longer boil generates more of a Maillard reaction in the beer and will increase the bready, toasty flavor of the beer.  A very intense boil will produce sweeter caramel flavors.  I will look into this for future beers.
  
• Mash at a higher temperature:  Mashing in the 152-160F range will result in more long-chain sugars in the beer that yeast cannot ferment. This will increase body and residual sweetness.  I've played with this a bit, but have not yet seen significant results from it. I may need to combine the technique with others above, such as increasing caramel malt amounts and adding calcium chloride.

While most of my beers have turned out fine, my "bigger" Belgian beers and my Scottish ale both tend to ferment a little dry and thin for my taste (and the judges' also).  I'm hoping that leveraging this information will get me a better beer in the future.