Option 1, is your original trip idea, however i think youll miss many beautiful places if you just continue, I would suggest this route for going directly to Mazatlán.
Option 2 sounds like a great experience and lot of desert landscapes to visit... however as security concerns, i'm not sure about some segments in your route as like between Cuatro Ciénegas-Torreón and Parral-Durango, due those roads are lonely and longrun. Currently the Parral-Durango is under construction (the highway is being expanded) so expect bad road conditions in that segment. BTW near Cuatro Cienegas theres a thermal pool similar to one like in Yellowstone (prismatic pool), hope you can visit it... also visit Puente de Ojuela (world tallest bridge in 1800's), abandoned mine and ghost town a must go in your route! located near Torreón.
Personally I would recommend you this option as your way back to the US;
https://goo.gl/maps/eCkwKIn your route back, you can visit many places:
-Historic Downtown of Durango and the old west villa (many US western movies were filmed there), there are trips from Durango downtown to the old west villa.
-El Saltito waterfalls (Durango-Zacatecas highway), just a small oasis in the desert with a waterfall, site of many western films, its just 1 mile from main highway
-Sierra de Organos National Park (20$ pesos fee entrance) , its a national park of rocks similar to Cochise stronghold in Arizona but bigger rocks, another great site of the filming of many US western movies. Just 5 miles from main highway.
-Zacatecas city historic downtown (UNESCO world heritage city), visit the city mine cave (Mina el Edén), visit Pedro Coronel Museum (international artifacts), Guadalupe Museum (reinaceinse pintures of the passion of christ), climb into Bufa mountain and take teleferico (cable car between two mountains)
-La Quemada (ancient ruins in a desert hill, from an unknow old culture similar to aztecs), UNESCO world heridtage site...
-Head north to Saltillo MX54 (4 lanes highway) and take a detour to MX62, to Real de Catorce, a must go of desert ghost towns, its a town located in middle of the mountains up to 10,000 fts high, great views, ancient caves, ancient buildings such churches, and mine, its a safe tourist place, this is where La Mexicana movie (The Mexican) by Brad Pitt and Julia Roberts filmed.
-From Real de Catorce you can just continue your trip to Laredo, TX, however there are some places such national parks, waterfalls in your route, (Sierra Las Cumbres), near Monterrey, its just some massive mountain ranges that you'll see from the highway.
Any questions send me PM