I have never used one of the pad diffusion devices but I find it hard to believe that a little pad with perfume on it will work any better than stick diffusion or candles.
I think you have two choices left: 1) lampe berger catalytic fragrance lamps or 2) an industrial scent diffusion system.
If you haven't tried catalytic fragrance lamps, I would start here. If you are unfamiliar, here is a youtube video about the fragrance lamps:http://youtu.be/QTnVwAAYOPE
The lamps, wicks, and scent fuel can be purchased relatively inexpensively on eBay. There is no open flame (except for the first 2 minutes while you are heating the wick) and the scent can fill an area very quickly. The lamps run until they run out of fuel or until you snuff them with the cap. I find that they are much more effective than candles. This is definitely worth a try as you can always resell the lamp on ebay if you decide it doesn't do the trick. I use 2 myself: one in the entryway and one in the living room and I usually run them for a couple of hours each day. You could always add a lamp for each room if you want to scent a larger area.
The other advantage of catalytic lamps is that you can make your own fuel using a favorite personal fragrance and 91% isopropyl alcohol (I use 10% fragrance to 90% isopropyl as a general starting point for mixing - so a 100ml of your favorite fragrance could make 1000ml of fuel. This may be too strong or too light depending on the fragrance). You can also scent your own fuel by using concentrated candle and body fragrance oils purchased online or essential oils purchased locally. For concentrated oils, I use a mix of 1ml of fragrance to 100ml of alcohol. Each fragrance reacts differently to the heat, so you really need to test each fragrance oil to see if it will suit your needs. I have had good luck with SaveOnScents.com. They have a sample program which allows you to purchase 5 1.5ml vials of fragrance to test for around $4 including shipping. When mixed with 91% isopropyl, each vial makes enough fragrance to burn for about 7 hours -- more than enough to decide whether or not you like the fragrance. (and remember, you need 91% isopropyl - I buy mine at CVS for about $3 - NOT 70% isopropyl. The 70% has too much water and won't burn.) I use my lamps daily and the wicks last about one month each.
The other alternative would be to use a scent diffusion system designed for public spaces such as this scentwave system:http://www.scentair.com/why-scentair...ons/#scentwave
I have considered these but decided to try the Lampe Berger first because the pro systems are expensive. But if you are looking for a seamless, professional result and money isn't an issue, this might be a great way to go.
For me, the catalytic lamps worked fine.