If you want to do some casual research for a future trip, you can get fare estimates using the Kayak skill. You can say, "Alexa, ask Kayak where I can go for $400" or "Alexa, ask Kayak how much it costs to fly from Los Angeles to Dublin." The skill will ask for additional information and eventually provide you with a series of options and price ranges.
For tracking your food, you can use the Track by Nutritionix skill, which lets you record your food intake using your voice, or ask for caloric values of foods. (Alexa does the latter by default.) Say things like, "Alexa, tell Food Tracker to log a cup of almond milk" or "Alexa, ask Food Tracker how many calories are in two eggs and three slices of bacon."
I suppose it's a reasonable first effort, and I don't know if the abilities missing can be corrected. The skill allows you to "launch" some channels (Direct TV, PBS, Amazon Prime) but not others (Tubi, Filmrise, The Roku Channel). Once a channel is launched, I couldn't find a way to navigate within the channel so it was back to the remote. While viewing DirectTV, for example, when I asked to watch "ABC", or view the guide, Alexa was stumped.
The next step in our Alexa flash briefing tutorial is to set up an Alexa skill for delivering the briefing. First, visit the Amazon Developer Console to create a new skill. Begin by giving it a name, then click “next.” You’ll be offered a selection of Alexa skill models to choose from. Select “flash briefing” from the list, then you’ll be met with a series of Alexa flash briefing options.
You'll notice in the lists below that many Alexa skills are called by using trigger words like open, start, play and ask. While select skills require you to use specific terms, others consider them to be interchangeable and will work with some or all of these phrases. Over time you'll begin launching your favorite skills by the words you feel most comfortable using. Initially, though, it can be fun to play around with each.