Annapurna Loop and Gokyo-Ri

My son and I trekked the Annapurna Loop (21 days) with Hari in Nov 2011. Absolutely outstanding trip in every respect with a great trail over Thorong La Pass and back down past Muktinath, Jomosom and Poon Hill. Followed by a few days in Kathmandu as tourists. My son, his wife and I joined Hari again in Sep 2014 for a trek in the Khumbu region to Gokyo-Ri (12 days). Another outstanding trek all the way. And I am scheduled to join Hari again in Nov 2016 for the three passes trek (25 days) just south of Everest. I keep going back to Hari because of my confidence in his ability as a trek organizer, guide, and friend...and the fact that he is local and his prices are very reasonable. 
I have backpacked in the Sierras for over 50 years and find a trek in the Himalayas easier in every respect except for the altitude. You have a porter and guide, you stay in a lodging every night, you order off a menu, showers are frequently available. All these details are arranged by Hari so all you need to do is haul your day pack with camera and wet weather gear. Standard advice for any trek: go as light as you can (you may not be carrying it, but someone else is), well-worn footwear (I use low quarter Montrail boots), walking poles, watch what you eat...stick with the menu food and you'll probably be fine. Altitude - there are rest days built into the treks to allow for adequate acclimatization. Altitude affects people different ways, I have had no problems up to 18,000 but may use Acetazolamide Tabs for the next trip since I just turned 69. If you fly from the US, try to get an overnight stay during your flight to Kathmandu (Singapore, Tokyo, Hong Kong, Beijing, etc). It will be a needed rest and help with the time zone changes. You'll arrive in Nepal feeling much better. 
The biggest issue is that I have confidence in Hari!