Have you thought about scanning your final prints rather then your negatives/slides? That way you can achieve the results you want in the darkroom and then make a straight scan from the print without much digital manipulation to upload to the internet or possibly make further prints from.
For scanning prints I have got excellent results from an older epson expression scanner, and the current epson V series of scanner are generally rated quite highly. Good dedicated negative scanners are getting harder to get hold of, the Nikon Coolscan range was very good, and Minolta also made some very good scanners. The cost of dedicated film scanners gets a lot higher if you are wanting to scan medium format as well, and even higher for scanning 5×4.