I'm not sure which car you're talking about, Mike, which does have some influence on my advice. That said, proper lighting is of significant concern to me, and almost every vehicle I've owned I've done something to improve the lighting on. Here're some tips:
The first thing to concern yourself with is whether or not your headlights will blind oncoming drivers. This has to do with the bulb/lens combination (whether the lens is designed to throw light and where the bulb throws light). To that end, driving lights generally throw light more like high beams than like low beams. They work fine for you on high beam settings, then, but can be problematic on low beam. I don't know for you what is a bigger concern, low beam or high beam lighting.
Brand makes a difference in the driving lights you get, but generally anything is better than nothing. I've used Hellas and off-brands. Hellas do work better.
These days, there are a lot of DOT-approved headlight replacements that, by themselves, are significant improvements. I recently installed a set of these headlights on my 2000 Ford Excursion. A little bit of rewiring was required (only because I wired them to keep the low beams on with the high beams). What I bought did come with an HID kit. Unfortunately, the HIDs it came with are 6000K bulbs. The number is the temperature color, and more is not always better. 4200-5000K is ideal. 6000K is advertised as "super white" but is actually a hair on the blueish side. Even so, the lighting is phenomenal. Because the bulbs are in projector lenses that are designed properly, there is no light thrown at a level that blinds oncoming drivers. I have not had a single person flash their high beams at me with them. For comparison, I get high beam flashes on my motorcycle frequently.
If you look on eBay, a lot of these lens setups exist for virtually every car. I would bet that just something like this, even with normal bulbs, would make a significant improvement. After years, headlights get old and don't throw as much light as they used to. Most people I talk to who complain about not having enough light are driving older cars with higher mileage (like yours).
Another option: Get some Sylvania Silverstar bulbs. No worries about DOT approval, and they really are better. They are not just higher wattage bulbs (actually they're standard wattage), but Sylvania makes a better bulb with them.
Here are some bad pictures of my truck with the new lights:
They're 4000K, just a bit below your ideal of 4200-5000K. They also have a Silverstar Ultra that is 4100K and is advertised to last 30% longer than the Silverstar (