I'll second the motion for the .300WM. I have one, a Rem Model 700 BDL, and it currently is my all around gun. Ammo is as easy to find as any other common round (as easy as it gets these days anyway). Mine has iron sights, which are accurate and reliable, but I shoot it with a 3X9. I've shot critters from as close as 3 feet to as far as 300 yds and it does the job each and every time. If you are worried about recoil (I might get chastised for this) buy the %50 reduced recoil shells. My stepmother had a broken neck years ago and couldn't handle shooting large rifles, but rather than go buy her a smaller gun we bought her those %50 reduced shells of remingtons and she never had a problem. I use only different rounds thru it, both remington core-lokt, 150 gr and 180 gr. Kills everything from prairie dogs and up.
And as far as your concern about bolts vs lever guns...why? Bolt action guns are reliable the same as lever actions are. Neither is perfect and neither is necessarily better. I wouldn't get caught up too much in the action of a rifle as I would the caliber and make.