Bear in mind that you can play the game at any level of graphic quality and when you find a scene you want to capture or view at it's finest, just open the 'options' panel (esc key) and increase the graphics to 'high'. Lower it back when you're ready to move on to keep frame-rates high. The only caveat is that changing bloom, HDR, or anti-aliasing requires saving and restarting the game. Sometimes it's worth it to see a scene in it's full glory. I did this for a long time before building a new system which could do it all.
My first and still a favorite mod is 'Portable Campsite'.
'All Natural' adds some indoor lighting effects as well as outdoor effects without much (if any) additional load.
'Immersive Interiors' which produces exterior views (including lighting and weather effects) through the windows can be a bit of a drain. Since it only effects interiors such as homes, inns and guild halls, you should be ok. It's really just the combat situations where a high frame-rate is essential.
Another great mod is 'CM Partners'. The basic version provides some traveling companions. Adding one more person in the scene shouldn't effect the frame-rate too much. CM Partners is also a basis for building new companions. Where CM Partners really shines is all of the custom partners that have been added by other modders as individual downloads often with unique features. Celebrities and movie characters are to be found in the collection.
I like using horses so I added SBsaddlebags which looks great and allows stowing some gear on your horse. 'Command Mount' lets you walk and have your horse follow along behind.
There are clothing, armor, and weapon mods that may appeal to you depending on your taste and don't effect graphics.