To address the OP's question, lots of others already answered the iPad-at-the-beach question: it's nearly impossible to read, and it overheats and shuts down.

An alternative to shelling out big bucks for a Kindle is to look at one of the cheap-o readers out there. I bought a Cool-ER (now bankrupt) for a fraction of the Kindle price. If it were to be my only reading device, I would have been disappointed. But as a beach-and-sunlight adjunct to the iPad it's just fine. Nearly all readers use the same e-ink display and offer a similar range of features: font sizes, bookmarks, etc. The cheap ones have a horrible UI and won't sync over the air, but for loading up a dozen books and some magazines before a trip they're great. Mine weighs about 1/4 as the iPad and will run for weeks without a charge.

Best Buy sells a Sony for less than $100, and you can find others on eBay for about half of that. I think it's a good alternative to schlepping books or struggling with the iPad. As a bonus if something happens to it, it's only 50 bucks.