Dr Homles has....... experience in teaching. (massive_impressive_value_available)
Dr. H has a lot of experience in teaching.
Dr. H has a great deal of experience in teaching.
Apart from the quantifiers David proposed, here are the adjectives suggested by the Oxford Collocations Dictionary for Students of English, 2nd edition. Considering that "experience" is used as a non-count noun, I'd go for any of the adjectives on the first line: considerable , extensive , great , long , vast , wide