This lake is worthwhile visiting for the drive alone, which takes you up through some beautiful boreal forest and beside Medicine Lake, a very curious lake indeed! Maligne Lake is beautiful, however it was very busy when we were there (late July), so consider visiting in the off-season. Also consider taking a kayak or canoe for a spin on the lake, for some of the best panoramic views. When we kayaked there, there were thousands of tiny trout jumping all around the kayak!
Well worth the stop-off on your way to or back from Jasper National Park. It can get quite busy, especially when the tour buses pull up. Be sure to take a stroll along the walkways and bridges, which offer different perspectives of the falls and associated gorge.
Note that the description says that this attraction is free - it isn't, and, from memory, costs around 40-50 pesos to get into. Well worth the small change! A lot of people make the drive themselves, however it's a long and arduous one and there's often road closures due to the surrounding villages fighting over who has the rights to this natural wonder. My advice - take a day tour, one which guarantees to spend a certain amount of time at this place (two hours minimum). Brilliant panoramic views, you can go swimming in the springs (however I didn't as they looked quite dirty - they haven't done the best job looking after this place), and can hike above and below the calcified falls. Definitely worth visiting if you're in Oaxaca!
The Cathedral itself isn't anything too special as far as cathedrals go, however it is provides an imposing backdrop to Puebla's Zocalo and is suitably disapproving of all tourists who walk within it's shadow. It DOES look very cool at night, if you stand positioned with it behind the fountain of the Zocalo and everything lit up.
Great location, quirky character, large rooms and seemingly recently (though not expertly) renovated. The downside is that the sheets are wayyyyy too small for the beds, there was a LOT of mosquitos in the room, and it was quite noisy at night. Certainly room for improvement!