Hi Carol!
I wish I could take credit for Paris tips but I haven't been there since 1997 ... must be another Janet. I HAVE been to Greece 12x since '99, including 5+ visits to Crete. For this reason -- and because you have ample time to research -- I do wish you'd reconsider yr itinerary. Is it based on Internet, or have you read guide books?? 2 that I find good on Crete: ROUGH GUIDE to Greece & CADOGAN's Greek Isles -- both available in libraries (latter not updated for 5+ years, but info on landmarks, history, ambience are timeless). ROUGh G is fab on history, scenery and - vitally - Candid about plusses/minusses of locales.
First, aside from no swims/hikes, it's not clear exactly what you DO want. Authentic villages? Architecture? Ancient Greek ruins? Dramatic landscapes? I'm wondering whether East-Crete choice is going to make you happy in all those regards, viz:
• Not been to Ag Nik or Sitia, but have read extensively & and talked to people who have. Feedbck: AG NIK =some nice buildings, isn't that historic, in 90s was big "package-holiday" draw for Brits. Port & lake-harbor lined with so-so restaurants/bars. Main site nearby is Spinalonga island; requires major walking. SITIA is a port RG calls "a pleasantly scenic if unremarkable place offering a plethora of waterside restaurants, sandy beach and a lazy lifestyle unaffected by ... visitors." Neither has an "old Town" as such. What is it that attracts you? PS: Elounda is basically an upscale resort -- I didn't sense that's what you're seeking.
• HERAKLION is "concrete city" -- ugly buildings thrown up after WW II, with the old Venetian stuff wedged in between. Bustling w. business, jammed traffic. Its museum is truly wonderful, and you can stay at a seaview hotel right near the huge imposing Fortezza, but I wouldn't recommend a long stay. There ARE fascinating historic aspects, but u need to be a true history buff. Knossos is a local bus-ride away.
• Both Stanbr & I have been SO entranced by WEST crete just because of all the aspects listed above -- and enjoying them does NOT require extensive walking. I should know; I'm 10 years older than you! (And both Stanbr & I have bum knees). Examples:
• CHANIA is "ground zero" for gorgeous Old Town architecture. Considered the 2nd Most Beautiful Old Town in Greece (next to Nafplio). A plus for slow-walkers, CHANIA has wonderful lodgings on flagstoned lane a few yards behind the portside, so you can explore the entire town on a series of SHORT walks... stopping every few minutes at a cafe or park. You can fly in to Chania, spend a couple of days just enjoying Old Town, and only have car delivered when you want to explore the area. Its museum (in a former church) is small and superb; walk counterclockwise thru 3 rooms, from stone-age to Hellenic in 20 minutes. The whole town (unlike those you named) is a visual delight of Venetian architecture.
• RETHYMNON can be an easy DAY trip - & u need not walk at all; they have a hop-on/ hop-off BUS that hits all the sites - http://dl.dropboxusercontent.com/u/17977187/RED%20BUS%20TO%20MILI%20GORGE3.pdf -- including a gorge & monastery.
• AREA - West Crete is TOPS for scenery, & no need to hike! For S. coast, bus down to Paleochora, stay the night (i hear that dinner at seaside has entire portside filled with tables), and bus back. In my earlier post, nothing I listed required major hikes; I don't do that any more, either!
• DRIVING "the LOOP" - from Chania to Herak, I suggest driving S. thru Spili (see map link I gave), see Phaistos, stay at Matala (or hillvillage Zaros) for a restful nite. Then amble NE toward Heraklion... maybe jump off @ Dafne for lunch & vineyard tour (it's wine country). Drop car at Heraklion hotel. See Museum & Knossos, depart via plane or overnight ferry.
If Stanbr & I can persuade you on west vs East, , happy to suggest hotels, resturants, etc. Now ... get thee to the Library!!