I love this thread! I often engage in television therapy. I find it a good way to wind down from the day. There are some shows that don't really soothe, but rather activate my nervous system instead, so I can't watch those at night. However, most of those mentioned here are soothing.
Someone mentioned The Forsyte Sage, so I want to add my voice to that recommendation. A really good mini-series from around 2003, it stars Damien Lewis (now on Homeland) and Rupert Graves (now on Sherlock). It is a (melo)drama about a family that covers about 40 years, late 1800s to early 1900s. Really good stuff if you like period drama.
Another show that hasn't been mentioned but that I find soothing as a cup of tea is Inspector Lewis, which gets shown here in the USA on Masterpiece Mystery. It's a sort of sequel to Inspector Morse, which I didn't like as much. If you like Foyle's War I think you will like Inspector Lewis.