You do not mention what acceleration your SEP is capable of. Presently power sources have to be rather massive. When, for example, your thrust is 1 newton but spacecraft mass is 10 tonnes, acceleration is .0001 meters/sec^2. See The Need For a Better Alpha.
If acceleration from the ion engines is a tiny fraction of the acceleration the sun exerts, the trajectory is a gradual spiral. The delta V from one circular orbit to another is well approximated by |speed of departure orbit - speed of destination orbit|. See the Stack Exchange question General guidelines for modeling a low thrust ion spiral?.
For example earth's average speed is about 29.79 km/s. Mars average speed is about 24.13 km/s. 29.79 - 24.13 = 5.66. A slow ion spiral from a 1 A.U. circular orbit to a 1.52 circular orbit takes about 5.66 km/s. (Here I'm assuming circular coplanar orbits and disregarding the planetary gravity wells).
Now let's look at a Hohmann orbit for the same scenario, a Hohmann from a 1 A.U. circular orbit to a coplanar circular 1.52 A.U. circular orbit.
Departure Vinf is 2.94 km/s. Arrival Vinf is 2.65 km. These total 5.59 km/s.
5.59 km/s vs 5.66 km/s? That's a difference of only .07 km/s.
Here is a graphic comparing sum of Hohmann Vinfs to the delta V needed for a gradual ion spiral:
The blue and red portion is like a sand chart. The red part laid on top of the blue gives the sum of the two Vinfs.
The grey part in the back is |destination orbit speed minus earth orbit speed|.
You can see for neighboring planets like Venus and Mars, they're pretty close. But a Hohmann to Jupiter beats slow ion spirals by a good margin. A Hohmann to Uranus wins by a larger margin.
But as you move from the sun, burns can be much more leisurely. Something in low earth orbit is moving about 4 degrees per minute. If you wanted your burn within 8 degrees of perigee, you'd have less than two minutes.
In contrast earth moves around the sun at about a degree per day. At 1 A.U., a burn within 8 degrees of perihelion would be about 8 days.
Jupiter moves around the sun at about a degree every 12 days. So if perihelion is 5.2 A.U. from the sun, you'd have more than three months to execute a burn within 8 degrees of perihelion.
So as you move outward from the sun, even ion burns start looking like impulsive burns.