Here's an older one. "Why Me Lord?" by Kris Kristofferson only reached #16 back in 1973, but spent 19 weeks on the Top 40 and 38 weeks on the Hot 100. This was a Country-Gospel crossover with very strong sales that took a long time to crossover to mainstream radio, and according to this Wikipedia article reversed chart direction a staggering six times!
Come To My Window -- Melissa Ethridge peaked around #25 but had around 40 weeks on the Hot 100 (1994-5) Haven't Met You Yet -- Michael Buble peaked at #21 but spent over 40 weeks on the Hot 100 (early 2010s).