re: Planning a my first Europe trip next year

You don't need a tour operator. You can plan everything yourself.

16 days is a tough nut because it's too long for one place but too short for a proper tour.

If you really love one of the bigger countries (UK, France, Spain, Italy, Germany), you could spend all of your time in just one of those doing a deep dive at a relaxing pace.

Or you could pick two countries and divide them with a week a piece. While rail is the best way to travel in Europe, the influx of low cost airlines means you don't have to plan an itenerary around two places close together.

All just depends on what you're interested in and the time of year.

If you want to be ambitious you could do a whirlwind tour: Amsterdam(3)--> Belgium(3)--> Paris(4)--> Swiss Alps(3)--> Munich(4) using an open jaw plane ticket and high speed rail in between those places. That's a lot of movement and relocation though and you better plan well. But it hits the highlights and gives you a pretty diverse taste of Europe in a short span.