receiver advice

For my home theater setup, I have a pair of Polk Monitor 70 speakers, a Polk center speaker and Boston Acoustic surrounds. Currently I'm running this through an old Harmon/Kardon AVR 20 II receiver I've had since the Clinton administration. 80 watts in front, 60 middle (I think), 20 in back.

SO... I'm currently leaning toward the Denon AVR-1613 receiver. I do not have a Blu-Ray player and usually watch movies through my Comcast cable box or Netflix. Other than that I watch sports or TV on my cable/DVR.

Question: what are the advantages of the 1613 vs. the entry-level 1312? Is it worth the extra $80?

I also use the Polks for listening to music through streamed bluetooth Pandora, etc. Is there another receiver I should think about? From the reviews it seems Denon is well thought of for audio quality.

whoops, I meant the 1612.

Currently I stream Pandora/Spotify from my laptop to my receiver with a Belkin bluetooth adapter hooked up to one of the auxiliary inputs so that would be my plan with the new receiver.

Is there any reason I should consider the similar Yamaha or Pioneer models? I would like to keep the bill in the low $200 range. I'm leaning toward Denon because from the reviews I've read it seems to have the best audio quality, plus the Audyssey calibration seems like a big plus (although I think the competitors may have similar features).