Its a big myth that 660 cc cars are not fit for long routes .. i can tell you my personal experience .. to put it precisely, ive traveled almost 50000 kms on long routes using 660 cc cars in the past 3 years .. between isb and lahore .. that is quite a lot as i was studying is isd and used to travel home lahore almost every weekend for more than 2 years ... 2 cars i used, 1) suzuki cervo SR 2008 2) Suzuki wagon R stingray turbo 2011 ... not even once, i repeat, not even once did either of those 2 gave me any concerns whatsoever on long route. if anything they were very comfy and easy to travel with ... 80 percent my journeys were on motorway and 20 percent GT road .. average speeds ranged anywhere between 110-130 on motorway and 80-100 on GT ... great mileage i got and great ride with neither car ever disappointing me ... most people just think because engine capacity is small these cars are only meant to be driven in city, well let me tell you its far from truth ..
Now coming to your query and options you ve shortlisted, stingray is by far the best .. in your budget, you can get a decent R grade 2011/12 model with low mileage ... Go for it and you wont be disappointed .. It has everything that PKDM wagon r doesnt have .. ABS, Fully powered, AUTO projection HIDS, Alloys, sofa seats and much more .. if you get top of the line one, you can also get push start, leather multimedia steering, climate control and paddle shifters as well .. Alto is also nice but much less cabin space than stingray and mostly ideal for female drivers in the house ..
Hope i was able to help .. Good luck