I'm 6'1" and wear a 35" inseam in jeans and pants. My legs are long, for sure, but at this length, there are still plenty of options for me to choose from (big smile here!). If you fit into this category, I think you'll be happy with what you can find online.
Alloy Apparel ($) will be your best bet for 35" inseam jeans. They have the most variety of denim styles in this length than any other tall store, from the ever-popular skinny jeans to bootcut and flare. I've bought several Alloy jeans in the past and they are all still holding up nicely. You'll find that Alloy's clothing comes in junior sizes from 1 to 25, but the styles are for all ages, not just the younger crowd. Try Alloy for their inexpensive options and variety.
EXPRESS ($$) is my favorite shop for jeans. Like I mentioned before, I am a 35" inseam, and that is the length of Express' tall size. The way that their denim is cut is the fit that I feel looks best on me out of all the ones I've tried. I know everyone has different body shapes and what works best for one person may not be the same for another, but Express jeans are my definite go-to. Their styles are typically between $50 and $100, so the pricing isn't bad either, especially when you catch them on sale.
Buckle ($$) is a great store for longer length jeans. They have a large collection of mid-priced and designer denim on their website. You can also find Buckle retail locations at malls across the country and they often keep a selection of long lengths in stock in their stores. While Buckle does carry some skinny styles, most of their jeans are of the bootcut fit with stretch.
Long Tall Sally ($$) doesn't usually have too many 35" inseam lengths available, but because they are such a great tall women's clothing source, it's always a good idea to look over their collection. Shipping on a $30 or more purchase is always free. They also have several retail locations in the U.S., Canada, the U.K., and Germany if you want to see their clothing in person.
Gap ($$) is a very well-known clothing company. And, most ladies of height are already familiar with their tall sizes. What I like about Gap is that they are constantly changing their collection. So, the variety is there. They are also good about staying on top of the current trends. If you visit one of their retail locations, you should be able to find some of their denim in tall lengths, although you'll find more online. Here's a tip...if you buy from Gap's website, you can return to any retail location for free, if needed. Free shipping on orders of $50 or more is also a nice perk.
New York & Company ($$) offers stylish and modern denim looks. Their talls come in either a 35" or 35.5" inseam and can be found in a wide size range, from 0 to 20. NY&C doesn't have quite as big of a selection as the other companies I mentioned above, but what they do carry are nice choices for any woman needing this length.
Metrostyle ($) gives tall women options for inexpensive denim. Most of their tall jeans collection comes in a 35" length and in the size range of 4 to 20. Metrostyle focuses on offering quality, signature looks at low prices...which when it comes to tall specialty sizes is often hard to find.
Lane Bryant ($$) is a well-known plus size retailer offering many different trendy looks. Their jeans are designed to give a more slimming appearance to the body. Lane Bryant's talls come in a 35 inch inseam and in sizes ranging from women's 14 to 28.
Roaman's ($) is also a plus size tall jeans retailer that sells 35" inseam denim. Their sizes range from 12 to 32. Roaman's jeans often come in a wide variety of color options which gives you plenty of fashions to choose from. Their look is a bit more classic than most of the denim at the stores above, which some will enjoy. Their pricing is also inexpensive, which no one can ever really complain about!
Zappos ($$) carries a small selection of 35" inseam jeans. Be sure to use their free shipping and free return policy to easily try out their clothing!