However, Nigel Pennick's The Pagan Book of Days surprised me. Sub-titled "A Guide to the Festivals, Traditions, and Sacred Days of the Year", it was chock full of interesting bits of info. Pennick is an Englishman who is tied into the local traditions of East Anglia, and many of the things highlighted are specifically British, but fascinating in that he is able to date when long-running traditions disappeared (a number with the advent of WW1, others in WW2, and others as late as the 1950's). There are also various calendars outlined (the "Celtic Tree Calendar" and the Runic half-months) and information on how daily cycles (specific influences on the hours) are used within yearly cycles.
Pennick also draws heavily on the Roman tradition, and it's amazing to see what "deities" were used to personify various things (such as June 8, the festival of consciousness, personified by the goddess "Mens"). The book (the bulk of which is just monthly listings of days and what's associated with them) is also liberally sprinkled with "Egyptian Days", which (like our own "Friday the 13th") are days of ill omen ... although for most he doesn't specify how or why they gained that attribution. There are tons of illustrations, largely classical drawings, but also featuring some very interesting sigils for phases of the calendar, some of which I'd not previously encountered.
There were plenty of "I did not know that!" moments in the book, although some I took with a grain or two of salt (for instance: "The Gnostic followers of St. Nicholas, the Nicolaites, taught that the only way to salvation lay through frequent sexual intercourse." ... talk about finding something special in one's stockings!) ... more often, though, these ran to obscure connections of deities (such at the patron goddess of the sacred hot springs at Bath, Sulis, being a manifestation of Neptune's wife Salacia) which may or may not be on particularly solid ground.
All in all, I found The Pagan Book of Days quite the pleasant surprise ... no where near as "fluffy" as I had anticipated, although having a lot of information (all the calendrical systems, for instance) that was of minimal personal use to me. If this sounds like something that you need in your library, Amazon can hook you up with a "new" copy (via their new/used service) for a few bucks!