saddles are extremely personal.
i will say this, even the stock saddle shouldn't hurt after 6-8 miles.
you might want to seek professional help fitting yourself properly to your bike, it's entirely possible your seat height is higher than it should be.
I run a similar saddle to 44. Selle Italia SLR Flow with titanium rails on my bikes.
Before you go to a shop or pay anyone to do a professional "fit", here's a quick fit check at home, here's the business:
0. Forget about knee over pedal spindle. Forget about saddle set back. Forget about Q-factor.
1. Measure your inseam. In stocking feet, put a book between your legs, spine facing up, making sure there is no gap between you and the spine of the book. Face a wall and make a small pencil mark being sure that the book is perpendicular to the wall. Measure this height. This is your inseam.
2. I use the Lemond Method for determining a starting point for your saddle height. Take your inseam and multiply it by .883 . This number is your saddle height from the center of the bottom bracket to the top of the saddle in a straight line with the seat tube. (This should get you close to your saddle height.)
3. Center the saddle on the rails and with bike on level ground, and level balanced on the saddle, level your saddle.
4. When seated on the saddle, your legs should be have a slight bend at 6 o'clock (closest to the ground). An interesting check for this would be to have cycling shoes on, place heels on pedals, and begin to back pedal. You should JUST be able to make them go round without your heel coming off the pedal. You should not have to rock your hips to make this happen.
With the "Lemond Method" saddle height, it will get you close, and you can make fine adjustments from there to get the saddle height just right. Leveling the saddle will make any saddle feel 100 times better, even the worst of saddles. But some saddles are just not comfortable or just plain do not fit. So it may take some time to get one that fits you well and you are happy.
Fine tuning your cockpit on a stock bike is a another set of parameters. You can adjust this with different length stems, moving the saddle fore/aft on the rails a pinch at a time, even moving your hoods/levers (road bike) up on your handlebars can help. Basically, you want your hoods coming off the bars to produce a flat platform for you to perch your palms. Some newer style handlebars are called "short and shallow reach". That means the bend out to the hoods isn't as far and the drops aren't as deep (I prefer these style bars). I've never liked that stretched out feel of a road bike. The bars have always felt too narrow to me. So I run a shorter stem with short and shallow bars along with a custom length top tube and seat tube taking saddle set back into account to get my fit. So I'm a little more upright in my stance on a road bike. This is custom, but that's what I do.
For the record, here's what mine looks like. The picture makes it look like there is a lot of saddle to bar drop but it's about 1.5" of drop (I need to take a side shot of this bike...):
Good luck!