My character is very high level and multi-talented including sneak and archery. He's a high elf and is not a super-archer. My main default use tends to be one-handed weapon in one hand and magic with the other (mainly conjuration, destruction and restoration). However, my archery skills is at 90 and sneak is at 100 so I have developed them with that character and I find using those skills to be a lot of fun. You don't have to start a new character to become very proficient in archery and sneak, although if you want him to be a super-archer you should probably concentrate on it starting at a lower level than I did.
I found the civil war storyline and quests to be my least favorite of the storylines and questlines in the game. I would still do it, though.
ETA - I will probably never finish the thieves guild quests because I don't want to give up the skeleton key.
Our characters are very similar.
I too am High Elf Destruction Mage (master in destruction) with a high proficiency in one handed weapons, Light Armor, Alchemy, Enchanting, Illusion (65) and Restoration (89) and I am fast building my archery and sneak abilities as well (once I started The Thieves Guild quest line and Dark Brotherhood quest line. Depending on my surroundings etc I could wear my enchanted glass armor set, or my bad ### destruction mage robe with my Morkei mask. He is a very diverse character whom is the best I have ever had in any role playing game. I really have been taking my time with this game and exploring everywhere and just adventuring and taking it all in. I can definitely focus on archery more going forward as I am really digging the bow's, and poisons I am creating. My characters level is 50 so I still have plenty of room to keep leveling up.
What is the highest level you can achieve out of curiosity? And has anyone found all of the masks in the game (I still only have 2) Morkei (regenerate magicka 100% faster) and Volsung (increase carrying capacity and breath underwater)
I guess the true beauty of this game is it can go on for hundreds upon hundreds of hours with the same character build. So maybe that will be my direction. Branch out my Destruction Mage to a cunning and deadly archer and assassin to add to his resume.