Hi Viridans,
If you create the flight plan, it will load into the GPS and if it's an IFR flight plan, ATC will give you altitudes and headings. Even if it's a VFR flight plan, you can slave the auto-pilot to follow the flight plan, and all you have to do is dial in altitudes and airspeeds. When you near the airport, you can even use the GPS to select your approach and the auto-pilot will follow that too (unless there's an unusually sharp turn) and again... all you have to do is control altitude and airspeed (use flaps accordingly and lower the gear).. and just turn the auto-pilot off for the flare and touchdown.
There are a few steps that need to be learned to do this:
-dial in your desired/appropriate altitude/airspeed
-engage the auto-pilot after take off
-select 'GPS' on the NAV/GPS selector
-activate the 'NAV' function on the auto-pilot
Then you can just sit back and watch.......
... but you said the key words..
i want to experience that as a pilot
Hop in the old C172 and practice practice practice, navigating. Plan your flights yourself (all aspects; time/distance, fuel burn, wind, weather, etc.). Learn VOR/NDB/ILS use until it's second nature (leave the GPS off). Work your way up to the jets and then use the GPS because you want to (not because you have to), but still plan the flights yourself. If you do use the built-in flight planner; study that flight so you "could if you had to" fly it manually. And even as you are flying by GPS/auto-pilot, back it all up and confirm you position periodically by VOR/NDB.
If there is one aspect to simming (I think there are many) that you could apply tomorrow, in a real plane... it's navigation :)